Single pole GFCI breakers are inexpensive too - Looking at Home Despot, the Square D Homeline 20Amp is $35. If you go this route, you'll need a breaker that is designed for the brand and model of your breaker panel and as such. The price typically ranges from $30 upwards and varies widely depending on your source.
They are not difficult to install but one must exercise caution when working inside a live breaker box. If you are uncomfortable swapping out a light switch or receptacle, then you'll want to find someone who is.
Having multiple GFCIs on a circuit is not a problem as noted by HotTubDan.