I have become a big fan of dry suits since I found the courage to take a blade to the latex neck and wrist seals. It now fits securely without interuption of bloodflow and being goretex I was able to paddle for hours this past Sunday in 80F+ and not break a sweat. That particular suit retails for slightly MORE than I paid for the Yak but I got lucky and the store were running a 20% discount on 'accessories' at the time.
A lot of kayak fishermen are using a combination of breathable stockingfoot waders plus a dry-top. The fit of the waist seal plus added insurance of a wading belt reportedly makes a good waterproof seal. Somewhat less $$ than a full dry suit.
I started out with the Farmer-John/Fleece combo and it was effective but I wouldn't want to have been paddling in that setup this past Sunday!
When sight fishing, look over your shoulder from time to time, you never know who's behind you