He's very pretty, and you're right - picking an active one is a good choice!
Don't worry, your fish will be fine for a while longer in his cup - after all, he's been in there for days or hours in the store. He'll be fine even if your temperature is 72... bettas *are* hardy fish.
So it sounds to me like you want to do right by Fishy but not break the bank. That about right?
The Aqueon looks a little better to me (and I agree with the comments on the corner tank - Bettas can see their reflections in corners). But the trouble with both those kits is that they include filters and lights (which are optional), but not a heater - which is really *not*. One has flake food rather than pellets. You can't tell how soft the plant is, etc. It'll include a sample of water conditioner, which will run out pretty quickly.
I'd recommend you pick up a Kritter Keeper, a preset heater, and some bits of decor for an absolute basics tank. You're going to need to buy water conditioner anyway because the kit samples are pretty small, so go ahead and get the littlest bottle of Prime or some other brand that neutralizes ammonia <- this is just important if you think you might miss water changes. Get a glass or LCD-stick on thermometer, whichever responds to your hand temperature fastest in the store.
- medium Kritter Keeper
- Hydor MINI heater
($5), soft plant
- Water conditioner (Prime)
- $7 - I've also used Tetra AquaSafe, and heard good things about AmQuel. Myates siggy has a link to a list of water conditioners
thermometer - $2 (Amazon is expensive at $4)
- Betta pellet food
That totals you something like $42... which is pretty comparable to a kit plus heater and thermometer ($24 + $9 +$ 2 = $35), and then water conditioner & food when you run out...