Canoe-Yak Fisherman - If I were to prioritize the criteria, they'd go something like this:
Easy/fast travel
Easy to load on top of vehicle
Budget of $500
Ability to carry myself + 50-80lb of gear including 12ft rods, rod pod, scale/tripod, bait buckets, etc.
Ability to carry 3 people
As stated in the posts above, my brother has a jon boat which sees very little use. I could easily buy a motor for that, using it for group transport while having a smaller craft for myself.
Really, there is only one vessel that comes to mind, even the $500 is attainable if you get lucky and find a used one. It'd be a Meyers Sportspal S-15 (square stern) if you ever think you might want to add up to a 5 HP outboard or a trolling motor. If not, an S-16 (pointed stern). Either will easily manage the total weights you plan to use a vessel for. Even down to an S-13 (square) or S-14 (pointed) works very well with two grown men standing and fishing from them.
Stability? More so than any kayak I have ever been in for standing, including my former Jackson Big Rig. And, my S-15 paddles just about like a large kayak. Yes, a canoe with its slightly higher profile can be blown around a bit, you just have to learn some of the tricks, just like from any smaller vessel on the water.
An S-13 was sold locally for around $400 as I recall. It'd be worth a look.
You'd be welcome to give my S-15 a spin if you have access to Lake Athens.
Brad