What to look for in stock AR XA table?

If it is in the described condition the price is OK. The cartridge isn't very good. Listen before you buy and you'll be ok.

Check the arm for excessive bearing "play". Gently take the thumb and forefinger and see if the arm rocks from side to side. The arm headshell should be square to the platter looking head on and not cocked to one side.
Check the internet for an original manual. If the unit is undamaged, you can tighten the bearings and lubricate it properly and make the damping work correctly.

Price is fair if no damage. Often, cover is cracked. Samujohn is right on. Search out data on the web and beware of spindle bearing damage. Remove the belt and give the platter a slow spin. Observe how long it spins and listen/feel for any issues. Consider re-lubricating spindle if not already done. Arm rest is fragile too. ( I've got spare parts if you need them. ) There are sights that offer mod suggestions. New belts can be found for around $8.00. This is a decent re-entry table for the money. Fully manual operation. Best of luck.

I know these tables and own one I intend to rebuild on AG (soon).

There are two parts that demand attention. They are the ball bearing and the small plastic circular plate inside of the lower bearing housing located in the "T" substructure . Should that white plastic piece be broken/worn or should the ball bearing have a flat spot , Don't buy the table. These parts can not be replaced. All the best.

The web site www.vinylnirvana.com is devoted to AR Tables and is a must view for anybody interested in AR's.

The site sells rehabed AR Tables and hard to locate parts . The site has an openly discussed relationship to George Merrill's and his groundbreaking AR T.T. mods ; Mr. Merrill has been associated for decades with significant improvements & secondary products made to vastly upgrade older AR's for the DIY crowd.

Vinyl Nirvana has lots of valuable AR information; a careful review of every page , every photo holds invaluable information on AR Tables. Should you consider the purchase an older AR Table, read with pleasure.