You certainly did try, and I'm sure you did your very best. :/ Some people really just don't want to understand, no matter what sort of logic and facts you put in front of them....
Sadly, in reality there is no 'cheap pet' as sadly so many people are led to believe bettas and other fish are in particular...
If funds are really the biggest issue, there are cheaper options. Like you said, Goodwill, Salvation Army, other thrift stores, Craigslist.....Sometimes you can find 5-10 gallons for just a few dollars.
Also, did you look at the Kritter/Pet Keepers? The Medium size are just about $8-$9 each and holds about 2 gallons. You could toss in a couple of silk plants, a terracotta clay pot(less then a dollar at most thrift stores; best cheap caves EVER), a heater, and there ya go. Might not be as 'decorative' as bowls....but its cheap.
Also.....if you're really pressed for cash and you could stand to wait a couple of weeks for shipping, these are the heaters I use in my 2.5-4 gallon tanks.
http://www.ebay.com/itm/-/2710315149...E:L:OU:US:3160
Just $6 each and they work fantastically. Only problem is the shipping time and the cord is a little short, but that can be fixed with a small extension cord.
With those heaters and the medium sized Kritter Keepers, each full setup, including decor, would cost around $20-$25....its bare minimum, but it will work just fine, and its certainly much better then the tiny cold bowls. Plus there is always the option of upgrade later on down the rode if you are able.
I hope this helps...