To get 300hp out of a 1996 bonneville se (non supercharged)? What would be the best way to go about doing it? Also what are the best mods for the money (most HP, lowest cost)?

300hp sounds a bit much, but if you got the money, I guess anything would be possible...

As for first mods, start with this Tech Info thread

How much can I expect to get out of a bonneville then?

Maybe with a Intense Head and Cam package (stage 4) for $3400.00

Gonna have to wait for the gearheads and/or gurus to answer that one. Anything I had to say, I would be pulling out of the wrong body part....

Thats a tall order but it is doable.
Start with Cold air intake and open up the exhaust (pem'* or headers).
Drop the tstat to 180*f and a fresh tune up.

Now your ready to dive into the motor and the costs rise quickly, cam, heads, intake etc.

How big is your budget? That'* the question.

I would like to get an idea on how much a high HP bonneville would cost to do, for the future.

But as for a budget right now, what can I do for under $1,000?
First thing I want to do is thermostat. Is 160* better to have than 180*? Intense makes both.
Next will be intake, although I can't seem to find any that are made to fit a 1996 SE.
After that I will probably start looking into exhaust bits.
Is this a good plan of attack, or should I do things in a different order? Anything else that should be done first instead of those few things?
Order of mods and parts/brands recommendations are welcome.

Intense makes an FWI that will fit.. Look for the 1997 FWI.
A 160 stat will set a "too cold" check engine light. 180 is more than adequate for where you are currently.

If you only have 1000 bucks, forget the exhaust for now. It'll be awhile before you can outflow it.

Look at rockers/PEM'*/FWI/PCM to start with and see what you think.