I'd suggest a combination of low and high tech for your solution:
1. Get either a used powered mixer and some speakers, or an unpowered mixer, and amp, and speakers. If you're just doing the solo thing and have no plans to expand in the future, then the cheaper the better. You could also get any variety of small portable sound systems for your local Guitar Center or online at places like Musican's Friend or Sweetwater.com. Don't use a guitar or keyboard amp for reasons mentioned earlier...it just won't sound good.
2. Download your tracks to an MP3 player instead of CD or DVD...unless you want to burn a new CD/DVD before every gig, or you want to run the risk of skips.
3. Get an adapter that will push the amplitude of your MP3 signal up to a level where it is good for your mixer. Those are easily found at the above stores for about $50.
4. Low-tech part: Write down the songs in order on a piece of paper. If you're really cool, make an Excel spreadsheet out of it.
Cost of cheap (new) small non-powered mixer: $100.
Cost of cheap (used) powered mixer: should be under $250
Cost of cheap (used) speakers: variable. I got some good ones for around $125 that have lasted me for years.
Cost of adapter: $50
Cost of set list: free
Keep smilin'
-A