This is a coffee table I have built out of a old piano lid that my girlfreind had found.
And these coasters to go with it. http://www.instructables.com/id/Piano-Key-Coasters/PRICE
Well the piano lid was free. GOOD luck finding one for free, or at all.
Everything els came out to around 70$
2x4 was around $4
Each leg was $2.65
After glue an other stuff it was around $70.
Of course it could be done cheaper though.