Okay, first of all, since he is sort of a child, to him that bike meant a lot to him. He wasn't interested in selling it, as he said in the film. As to the sequel, it really isn't one: Just another Pee Wee story, which sucked.

The Pee-Wee movies are more like the old Ernest movies; they're not related to each other. That's something the IMDb people aren't getting in some topics.
No he shouldn't of sold his bike regardless to what he could of gotten. I mean would you sell your most precious prized possession if you felt so strong about it? It's like me selling all my Resident Evil collection, my HDTV, my PS3 and every man dcor in my Man Cave. It just isn't done.

From what I can tell, every Pee-Wee production is its own standalone story. Pee-Wee's Big Holiday more or less pretends Big Adventure didn't happen. Despite this there are a few minor "in jokes" referencing the older film.

In retrospect, I think that Big Top Pee-Wee was a prequel, as it clearly takes place in an earlier decade.
Much better way of looking at it. And we can assume Vance the pig joined Mace and the circus, while Pee-wee and Gina broke up, so the former moved to the city to start over.

I really liked
Big Top Pee-Wee
, but I admit at the time I was disappointed in the lack of continuity.
In retrospect, I think that
Big Top Pee-Wee
was a prequel, as it clearly takes place in an earlier decade.

I'd say he customized it himself.

Sure, he would have had money to buy another bike like that and a lot more, but at the same time, it's a one-of-a-kind bike. Maybe just for that reason, he didn't want to sell it. And who knows if he could actually get another bike like that.

We have clearance, Clarence.
Roger, Roger. What's our vector, Victor?

He wouldn't sell his bike for all the money in the world. Not for a million billion
TRILLION
dollars!