What ever boat you buy make sure you leave some cushion in your discretionary income, you buy a boat to relax and have fun not to stress out about its impact on your monthly budget. Remember to factor in insurance, gas, storage if needed.
All that aside, jet bosts are a blast, you will have very hard time matching the performance and handling, with a traditionaL boat. Compared to a stern or v drive they are brick simple
Size...
I have never heard anyone say "I should have bought a smaller boat".
New vs. Used
If you are mechanically inclined, don't need everything to be perfect, and don't have tip have the latest and greatest, then a low hour used boat can be a great option. Someone else has already taken the depreciation hit, saving you a bunch of money.
New boats are like new carts, there is an undeniable satisfaction to buying new, plus you get a warranty and all the latest tech.
Good luck., happy hunting,
Andy