No you can’t get a turboprop for $150k.
When you say Atlantic I’m assuming Bahama’s, Bermuda and from FLL a straight shot to like North Carolina?
How many people and how much luggage?
If anything look for a late ‘60s or early ‘70s normally aspirated (non turbo) Piper Aztec.
At moderate power settings a good one will cruise at 160 kts TAS and burn 24-26 gallons/hr combined.
Theyre in your budget but being an old grumpy mechanic who is very well known with Aztec’s.
Pay him $1000 above his normal fee as he’ll be worth it 30 times over if it helps you avoid a toad.
Reason being they built the last one in like 1978 and not every owner may have been as diligent as required with repairs and AD’s.
Ive got 600 hrs in a 1966 Aztec C, honest airplane with a 2200 lbs useful load.