when you ask if there a hardy fish " Yes" betta's come from mostly Asia and Thailand Canbodia, Myanmar, vietnam, malaysia. So there is sevral places they come from. Most of the vail tail strann comes from the rice pattes of south Asia. when people tell you that they live in small bodys of water and can there for be housed in a 1/2g bowl. While that's totally off base. Here's a link to the so called small bowl of where most of the betta's in the market place got there start.
http://www.bettadreams.com/ricepaddies.html
There not the beautiful long fined fish you get from your storie today. Those are a line breed fish for finage,color. There a short fined fih who's colors are some what discolored and almost bleached out. Here a picture of a wild betta pi from Thailand
I got this male in a shipment of females from wal-mart,normally I'll only buy betta's from there if they've been mistreated or I run across a find like this one. Now I beleave you asked if betta's from a petshop are good stran. will most betta's bought in a LFS are already around 2yrs old and only hve a couple of spawns left in them { If that. } Now your just breeding to try it so you don't have to worrie with colors or finage to resell. The bad thing about the breeding for color useing two fish with close to the same marking or color is that you have no clue as to the color of the parents and there for the color your fish are may or maynot be the color you get. For a sample if the male is Blue over red and the females is red over white. Your fry could come out with nither color of the parent or very little if any, the reason being is there parents may have been a totally differnt color. Now they females will determan the color of 90%of all the fry. But here again line bred for selling and not for color is the key here.
If your breeding to get a sertan color don't go store bought for just that reason they are bred to any color any female that will bred with the male. 100% of all betta's sold in a chain store are bred just to mass sell and not another thing. 100% of all privite breder bred for either color or fins. There is a 1000 reason I could say not to go chain store for your breeding. But those are my reason and your just breeding to try it. Now here's alittle tip before you start breeding just to bred.
Be ready with the fry tank: leave the father in the tank for the frist 3 to 4 days. He will teache the fry to go to the surface for air and implant the father roll in the males. If using a 10g tank lower the water level to half. also the most important thing here is.
The avrage betta fry is between 200 to 300 fry even on there frist fry.
The betta's born togeather can be housed togeather for up to 6 months.
Be ready with at least 100 to 150 jars to house the males after they reach 6 months. They will start fighten after that and will need to be broke up.
Make sure you have a place to either give away the females and slae the males. Most all petshops wont buy the females.
Good luck and happy breeding!!