Been years since I lived there, but I used to live in Bradenton and keep my boat in Tarpon Springs. At the time to dock my cat at Twin Dolphin Marina (Bradenton) was about $1,000US per month. I only paid about $250 per month in Tarpon Springs. Keep in mind this was about 10 years ago, but I expect the relative costs are still much less in Tarpon Springs.
There are many good anchorages in the area....all the way from Tarpon Springs to Key West. Great cruising ground.
There are a couple of SW
Florida anchorage guides available (some on-line -- plus lots of on-line discussion of course). A search should easily turn them up. Look for "A Guide to Anchorages in Southwest Florida" originally produced by "BAIL". Not sure if it is still in print, but it was quite well done. See cruising guides for the area too.