Tojiro has a 155mm stainless DP Deba for around $48 on CKTG. I have one for inshore species (fluke, stripers, blackfish), but I haven't gotten to use it yet. I would check out that Deba. I prefer carbon, but with fishing stuff, I went back to stainless for easier maintenance. Tojiro Shirogami or Tanaka KU finish 165mm Deba's are $80 if you want a Carbon steel Deba without breaking the bank! What size/types of fish are you breaking down?
The gyuto and Santoku are redundant. I would get an Artifex 210mm; it will hold an edge better than the Tojiro DP series (Vg-10 steel) and sharpens easier. 150mm petty I would get the new Artifex petty, or the Fujiwara SS or Carbon 150mm petty; these are around $50 or less.
For sharpening: http://www.chefknivestogo.com/3pcstoneset.html
The Artifex 210mm and 150mm petty are around $130 for the pair. Stone set is around $140. If you want a finer stone than the Rika 5K, I would look at the Shobu San for $80, Ozuku Asagi Koppa for $70 or the Jyunsyou Koppa for $50. I like a J Nat for finishing off the edges; they tend to give the edge some bite due to the variation of the natural particles in the stone. The Shobu San does a really nice job de burring steels, even M390 and leaves a nice edge. The Ozuka is a bit harder stone, and leaves less bite than the Shobu, but a slightly smoother, more refined edge. If you just want a strop to deburr, get one of the leather pads, or a piece of Micarta knife handle material and sand it with 80 or 100 grit sandpaper and strop on that. The Micarta when sanded will have a fuzzy surface and works to deburr the edge like felt or leather does.