Your's is a really good question. And by the way your male common guppies may have already partially inseminated your fancy females.

The wild males aren't interested in bothering you fancy males. They ARE interested in mating with your fancy females.

A wild female (of choice according to studies) will select three males for mating just after dropping her last batch of fry (they are especially impregnable for 24 hours afterwards), There seems to be a survival factor in carrying fry from several males. That means that your females may be carrying and storing sperm from several males.

It would be interesting to see if any of your females have fry whose reduced size and tail length reflect a "wild" or common guppy x fancy guppy mating. It would take you a few months to find out.

I think you would be better served to do a Google image search for the fancy guppies you are interested in. Or maybe search for fancies to cross to yours. The colors you like are out there, I’ll bet.  You might search for Giessen / swallow guppies or multicolor guppies or even the better double sword guppies.

See also http://www.picsearch.com/
and maybe
http://www.ixquick.com/
http://www.ask.com/?qsrc=119&o=0&l=dir
http://www.alltheweb.com/?cat=img
http://www.search-22.com/downloads/images.php

Check out the show images and the "store" offerings at this site: http://www.ifga.org/
Check out their links too.

Our wild guppies are usually called common guppies. Although there are a number of laboratory strains of guppies based upon wild ones, few people are going to spend the money (maybe a couple $1,000) and endure the red tape to collect wild guppies these days. The exception might be a university group doing field or behavioral research.

On the other hand, guppies, like so many other creatures have gotten loose in places like Florida and Hawaii. Enterprising individuals will net them and sell them, mostly as "feeders" for larger fishes.

It took some pretty dedicated aquarists 40-50+ years to begin to develop fancy guppies like we have today. It wouldn't take you that long, but you might need 4 to 10 years and maybe 6 to a dozen fish tanks to line-breed adults and sort out fry so that you can reproduce guppies probably all ready around. :(

I'm sorry to sound that kind of note.

If you were to them re-mate your fancy males to the fancy females, after the common guppies had been removed from your tank (oh man! now we're spending your money!) and after the fancy females dropped, the more recent sperm that they store "usually" will “out race” the older sperm (stored in the female’s ovarian walls) to fertilize the next batch of matured eggs.

You may know that a pregnant female guppy can drop fry, on a more or less monthly basis, six times after mating. If that is news to you, please make time (that most precious of all commodities) and read through the first several sections of Immediate Help. See the link to the upper right of these pages.

Indeed, though this sounds very cold, you probably don't want to save the fry born in your tank over the next month and a half, Some will be fine, but some will be mongrels. If you live in a cold climate, leave them outside overnight this Jan or Feb.

If you don't want to kill them, leave them as is, but you will find that if you indiscriminately breed those guppies, they will get smaller and smaller until you have just slightly better common guppies.

I think common guppies are great, but I wouldn't mix them with fancies. (Imagine keeping an unfixed male mutt with your show winning female poodle.)

In fact, there are strains of what are either fish of another species or more likely just stunning strains of wild guppies called Endler's livebearers. If you Google search Guppylog you will find lots of references to Endler's livebearers or Poecilia wingei. Ironically if you go to Google and search for Guppylog and Endler's livebearers you may get more hits! (That may be because of the buggy server GL is on at the moment.) Of course if you search for Google for just Endler's livebearers or Poecilia wingei you will risk being overwhelmed. ;)

I have five tanks of them in three different body color morphs and obviously like them a lot. But I would not mix them with fancy guppies.

Here's a neat site on Endler's. He has really changed it though and obviously feels that they are a distinct species. My heart says yes, my brain (such as it is) says no to the separate species idea.
http://members.cox.net/newcomb1/endlers.html

If all of the fry from your five fancies and your common guppies that were born this year lived to grow up and have fry of their own (while the parents are still dropping) and their fry all survived to drop fry, you would be the proud owner (conservatively) of a couple thousand to as many as 60,000 guppies by next Christmas. (Ho! Ho! Ho!)

See http://www.guppylog.com/story/2005/2/20/15155/6360
for how this could work out. Somehow the storage system has pasted two stories together but especially  read the last 4/5s please.

Somewhere along the line all people keeping guppies have to do something about additional fry. I wish that wasn't the case, but reproduction designed so that maybe a couple of pairs would survive to carry on the species and strain in the wild, creates a huge problem in captivity.

I really like your idea of creating radically new guppy strains. I'm afraid though that you would "burn out" on guppies trying to do that.

A really good book on the shelves of the big box bookstores is the $10 Aquarium Care of Fancy Guppies by Stan Shubel (TFH Press). Browse it in their beverage area. Even if you decide not to buy it, you will glean some great info from it.