Carol, here are three ideas for enjoyable, low cost experiences in Amsterdam:
1 -- There are public buses that you can catch from a platform behind the train station, which operate almost like "hop-on, hop-off" buses for the Netherlands countryside. They offer several routes. We chose the Waterlands. Cost 10 euros per person for the day. It took us to Edam, where we got off and spent some time, then we caught a bus to Volendam, had lunch along the harbor, then took a ferry (extra fee) to Marken, then a bus back to Amsterdam. Spectacular day.
2 -- We did a cheese & wine tasting at Reypenauer (15 euros in 2014) and for an extra 5 euros, we got tickets for a canal boat tour. Delicious cheese ... we are now addicted to aged goudas! And you have to take a canal boat tour in Amsterdam.
3 -- There was a free lunch-time concert every week at the concert hall in the museumplein (just past the Rijksmuseum & Van Gogh museum). Normally it's on Wednesdays, but the week we were there it was Thursday. So if you're there mid-week, find out if they're still doing these. And get there early. We saw two amazing pianists.