home depot's or lowes will cut your lumber for you, however my local stores have signs all around the saws that say ' no accurate cuts ' and first 2 cuts are free, then 25cents per cut afterward'
once i needed to get some plywood cut, and the employee told me he can't cut wood to less than 12inches in width because of store policy. i explained i am buying the wood at regular price, i just don't have a helper to rip it on my table saw at home, but he wouldn't budge. so i just ended up finding a different employee in lumber and he did it, with no problems, and laughed at the 'store policy' i was told ealier.
best thing to do is get home depot to do the cutting for you (if you dare) or borrow a circular saw from a friend / neighbor. you could also go to a local walmart and *rent* a jigsaw or circular saw from them.