I am needing to replace my front fish finder on my boat.I am looking for a good one for as cheap as I can get by.I was looking at the Eagle Fish Mark 320 and 480.I need something that will have good definition.I want to be to tell what I'm looking at as far as baitfish and whatnot.

I use the Eagle Fishmark 320.  Very very happy with it.  Marks everything clearly.  Never had a problem with it, and it's made by Lowrance, so the quality is very nice.

Jason

get the lowrance X135 thats what I have. and you can see bait fish,brush, every thing you need to see

I just bought a new 320c off a guy on this board for $110.  Try ebay.

Either unit, 320 or 480 will give you excellent seperation.   Shop around, and as suggested, try ebay.  You can find some good deals on discontinued models.  I bought a Lowrance X87 (320 pixle) a while back with temp Xducer for $150 from Cabela's.  Had absolutely no need for it, still sitting in the box beside my computer now, but at that price, I figure one day I'll find something to use it on.    Actually, I still like the x-75, 240 pixel units, but the 320 and 480 units will give you better seperation on targets close to the bottom or other cover.