Does anyone know if it would be possible to transform a flatter style speedboat into a bass boat? Been looking for a bass boat but couldn't find one for cheap and then saw a speed boat with trailer no motor for 150. Just wondering if it was possible?

I don't know much about boats. It seems plausible. Maybe more a question of your skill level and what your desire is in final.

If it were me doing the work than I would keep looking for an old bass boat that needs an overhaul. So long as the integrity of the boat warrants said overhaul.

I'd rather do a Jon Boat conversion. I plan on doing one with my dad after he retires here in a few years.

I think you're probably better off waiting for a boat like Rick described. With the speedboat you're probably gonna have to do a lot of work just to get it to the point of a bass boat needing an overhaul. As suggested above, the jonboat conversion is also a great option.

Don't get me wrong I see the allure of a bass boat. Thats why I have a babied Ranger. But, I didn't start out with that. Started out and still have a 16ft aluminum Grumman my grand dad gave me. It was all I needed to get on the water. Still to this day is more than enough. Everyone always thinks bigger/ more expensive is better. I like to keep things simple and enjoy my days in the aluminum boat fishing with only 3 rods. Plus, don't know if my grand dad has something to do with this, but I catch more and bigger fish out of his boat. 

Would taking the top part out and putting a deck in be enough? Or what else would I need to do besides the obvious like storage and seats?

It might be possible, but I doubt it'd be cost effective. You'd be sinking a lot of time, money, and energy into building something that won't be as fishable as something you could have put a lot less into. Not to mention, if you're looking at a boat for $150 I would think it's in absolutely horrible shape to begin with. If I where you, I'd do as others recommended and either deck out a john boat or wait till you could find an older bass boat. You might want to even look at 15-17 foot aluminum v-hulls. Those will be cheaper and I would bet would still be more fishable than a converted old ski boat. 

Anything is possible, but being practical and financially feasible probably not.