i would not recomend your FW reel for SW use. it wont last long in the salt water enviroment and a nother draw back is that most fresh water reels wont hold much backing! not a big deal if you are fishing for seatrout however when a big red fish or tarpon grabs your fly istead, your day may come to an early end when you are left with out an inch of line left on your reel. e-bay will be your best bet. if you are going to be fishing the salt more than once or twice a year you might want to spend a little more and get a quality combo that will last for years instead of spending $150 and up-gradeing after a while. you could get a nice combo from Burleson sporting co.(www.burfish.com) which is selling a SW large arbor reel/rod combo with backing and fly line for $271 which you will be close to that amount if you spend $150 for a combo, then $40-$60 for fly line and a nother $20 for backing. if you dont want to go that route then check out the redbone fly rods. i had a 10wt redbone as my first SW fly rod and it was well worth the money it was about $100 at sports authority, and you could check e-bay for a reel. good luck!
(sorry if recomending that web site was against the rules, still not sure who we can recomend and who we cant, just trying to help the guy find quality equipment- not trying to "plug" any one's business.)