It all depends on your experience, skill level, and available tooling.
There are some things you can do to save money if you have the know how and ability like making your own engine/trans mounts and oil pan.
The easy answer is, no, you likely can't do an RB install for less than $3k.
Expect to spend $1200+ on an oil pan and mounts alone.
Search through the RB forums and people's build threads to see what people are spending their dollars on, and how many of them they're spending. Most basic swaps come in around the $4-5k mark, if I'm not mistaken.
Take my numbers with a grain of salt, since it's been some time since I did my research on the RB swap. The cool factor is huge, but the $/hp is what turned me off of the swap, since I'm also a student with limited income.