K.L.
Ikea has a simple train set for $10. An additional 3-piece train set is $3.99 and the 10-pack rail is $6.99. Unfortunately, you cannot purchase these online but there are plenty at the store in Frisco. The sets do have small parts, so they are not recommended for children under 3. That being said, my daughter, now 3 1/2, has loved her trains for over a year.
http://www.ikea.com/us/en/catalog/categories/series/11673/