They don't appear to be as readily available as say, plain fancy guppies.
this site Enchanted Mountain Guppies
seems to be selling a trio for 25
It does appear (mostly based upon the bid prices on aqua bid and how few places i'm finding that sell them online) that if you get a good breeding trio, and kept the strain pure, you could potentially make your money back if you breed and sell healthy fry.
I would suggest keeping an eye on them on aquabid.com and craigslist, ebay, along with the classifieds on this website too. eventually you should be able to find some for a good price.
Blue Moscow guppies doesn't seem to be quite as common as black moscow. and i've only found one place so far selling purple moscow guppies. So I guess seeing as your question is could you make a profit, my answer would be yes. with a healthy breeding trio you could end up with hundreds of fry in a short period of time.