There are people way more knowledgeable than I am, but for that money a lower end B&W Lowrance maybe, Eagle pretty much the same thing...but if you want the best out there HDS is the way to go. The 5 is higher than your price range, but it is well worth the $$. I would get at a minimum the 7, but the 8 has the softkeys which are :AOK:
Good luck!