What motherboard does your friend have now? It would be easier, but a bit above 3k, to just swap the CPU for an AM3 Athlon II. You might even be able to pick up a used one somewhere. Used you might even be able to find an Athlon II X3 or X4 in your price range if motherboard has support. Core unlocking is not a guarantee even with a motherboard that supports it. My Sempron unlocked, but my Phenom II X2 560BE did not.
http

/www.flipkart.com/amd-athlon-ii-x2-270-processor/p/itmdf7rf2k89ezzg?
pid=PSRDF7RFUC8QVFAP&ref=59653d87-395d-46ab-82b4-489621657ffc