Hi David -
Unless you have some family medical emergency or something you need the money for, I would suggest that you do not sell your mineral interests. If you just really, really want some cash to play with, then only sell a portion of your interests, like 1/4 or 1/2.
If someone wants to buy your mineral interests it is more than likely because they know something you don't. And from my experience, their first offer is something along the lines of 1/3 to 1/4 of what they are actually willing to pay.
I have it from a very qualified authority that mineral acreage in some parts of the Permian and other Basins in West Texas can go for as high as $30K an acre if it is unleased and $10K an acre if it is leased.
Not everywhere, of course, but $1,500 - $2,000 an acre sounds like Chump Change to me.
Post your legal description(s) and I'll see what is happening in your area for you.
If you want to post your legal(s) privately, accept my offer to become A Friend on The Forum and you can send it of them that way.
Hope this helps -
Charles Emery Tooke III
Certified Professional Landman
Fort Worth, Texas