looking to put some electronics on my boat but  on a budget whats your guys opinion on the best for lets say under 500

Lowrance elite HDI

helix 5

A single unit or more than one?

 

What sonar technology do you want and do you want GPS/mapping also?

Lots of new models coming out and the discontinued ones are on close-out sale.

Don't overlook Garmin echo map units with chirp Love Mine,  Jaa

You can get away with size and efficiency with the Lowrance Hook series they mentioned above. 

I've been looking at the hook 7. You can get them at bps with nautic insight and a cover for 399. Does anyone have any info on these? Good or bad? 

I have a Helix 5 on my smaller boat and I think it is great.  I have also heard good things about Garmin, but I don't have much experience with them.  I moved from Lowrance years ago and probably won't go back. I had an HDS that quite obviously was not waterproof and it cost me a tournament or two (three different units in three different tournaments), so I just don't feel right recommending them.  That said, I know a ton of guys who love them and will always use them.

On a budget, though, I'd check out the Helix.  JMO.