I have one and it is quite nice. Personally, I prefer it over the Ceiners or any other after market model. There are plenty of posts about them here on THR and elsewhere on the Web.
Many folks feel that it's better to simply buy a good .22 pistol. Me, I have .22 pistols, but once in a while I prefer plinking with my Beretta and .22 ammo.
As for buying one, they are seen now and again for sale here, on the Beretta forum and rimfirecentral forum.