...or try to make sure you keep the mechanical rights to your track - make sure you're name is on the SAMRO forms so you get your royalties when it's played on radio - it's possible that could be worth more than what you could sell it for (depending on the artist and the beat).
In rare cases you might be able to negotiate the publishing rights too, but not many (established) artists will agree to that.
I only sell beats to record labels, not artists. That way I get to keep creative control of what happens on my beats, as well as the abililty to negotiate publishing and royalties with the artist.
Also,,, if you have a studio and the artist records with you, make sure you factor your production time into the deal.
but yeah,,, like mr. c said, use the opportunity for marketing yourself or make connections, we're in an embryonic industry so we all have to think like hustlers.
so yeah,,, free beats are not unusual - don't take it personal,,, i'm sure artists would love to be able to pay R20k a beat if they could, but the truth is most projects are made on a very tight budget.