|Technology and Science Summer Programs - a great list from the MIT Website|
Take a look at the MIT Website to see a list of summer programs, many of which are truly affordable.
From their site: "Most summer programs admit all or most students who can pay the (high) tuition. However, a number of competitive-admission summer programs select only the best students on the basis of merit and are often free or comparatively affordable. MIT offers four of our own and more links are provided."