Ah hell, if you are willing to spend $34 dollars on it you can get the five gallon I got at peco. I also found a cheaper pre setup tank at petco that was 2.5 gallons for cheaper. Let me link them to you. They are pretty decent tanks. All you would need is the heater, the gravel, plants and a hideout and it should be set up. Get silk plants though over plastic plants. And a thermometer is good to check on the temp of your tanks water. Also water conditioner, I use API which works great for me and was recommended to me by a friend of mine who is actually a hard core aquariust and a marine biologist. He's a big shrimp fan too and almost came to Texas to kill me with a claymore when I said I wanted to get shrimp and my tank isn't fully cycled yet. (still waiting for tank to cycle to get two cherry shrimp to clean the tank)
Five gallon for $34 dollars. This thing is great and I have had nothing but good experiences with it. It is acrylic rather than glass though but it shouldn't matter really unless you throw it around or beat on it. Just make sure to clean it with a sprung that was made for acrylic tanks. Also the filter works wonders and isn't too strong for the fish though I still put a plant directly under it to redirect the current or break it a little. This tank is also big enough to be cycled and if you want to get an african dwarf frog to keep in the tank with your betta than five gallons is the minimum. Anything smaller keeping anything aside from a few shrimp can be dangerous because of the ammonia buildup.
Here is a 2.5 gallon for about $29 but the downside to this is you can only keep the betta in here or else the tank will be overstocked and ammonia levels will build up too quickly.
Oh and that second one has the same filter as the first one so it's still got that filter I like so much. Only in a smaller tank after cleanings let it run a while before putting the fish back. That thing can have some spuratic spurts when first starting up again. It's not so noticeable in the 5 gallon but in the 2.5 gallon it might push your betta down into the gravel or make it rough to swim through. Once it gets going though it should be just fine.