The choices are endless. Some people collect salt and pepper shakers. Some people collect Coca-Cola memorabilia. Matchbooks are fun, as are collecting Santa Claus items. Collect cat or dog figurines, or pictures of chickens. Flea markets are a great source of low-cost items in the category you want to collect.
Possibilities are endless. Perhaps a trip thru a discount store can spark an interest in an inexpensive item that can be built upon. There are salt & pepper shakers, decorative bowls and all sorts of figurines with many themes. Boxes come in all sizes, material and cost and are practical.
You can easily collect stamps, tea bag tags, coins, and bottle caps. Nature will provide shells, butterflies, rocks, and animal foot prints. Also try quotes, jokes, autographs, and book marks.
Some fun and different things that are not expensive to collect are vintage Cracker Jack and Gumball charms from the 20's-60's, lucite purses, old cameras, vintage planters, vintage office supplies.