There are so many possiblities it is hard to answer your question. You will be there during the heart of the fishing season so if you want to use a guide, book early. Take a look at this site and you will see the late run sockeye peaks in July. Fish Counts - Sport Fish - ADF&G
One low cost option would be to fly fish for sockeye salmon on the Kenai, if your interested in that then send me a PM and I will give you details. Another idea would be to contact one of the air taxi services that operate out of Lake Hook (next to the airport) and inquire about a fly out to a remote salmon stream.
Lake Hood Seaplane Base, Anchorage Alaska Air Taxi Services
If your not particularly interested in fly fishing, but just want to go fishing, then check out the guides near Deep Creek or the Kenai River, most use bait or plugs so if you want to fly fish you will have to do some research. Some of the guides do float trips down the Kenai for Rainbows, but make sure they fly fish and not back troll plugs.