Since I have a very lightweight table (Rega P8), a record weight is out of the question. A clamp isn't, and I wanted a very light one of those. I found a product, the Molekula, whcih is made by the same company that makes my platter mat, Hexmat (I have the Eclipse which is excellent) that pushes down on the spindle and eliminates much of the effect of record warpage. I only use it on warped records. You can buy it directly from the company in Hungary and it is also sold on Music Direct (mats only it seems). I remember buying one of them direct and it was easy.
It looks like they recently came out with a record mat/clamp combo that looks interesting....