Years ago I had a cheap corner sander (hand vibrator) that I disposed of on Craigs list. But I have gotten really tired of hand sanding in corners, so based on recommendations from others, finally decided to order a Bosch 1294VSK corner details sander kit.
The sander arrived, and in the brief use so far, appears to actually sand, not just vibrate, and also has good dust collection.
But the big gloat is the discovery of CPO. Their web site was efficient, and promised free shipping the same day. Their price was only a couple dollars more than the cheapest web sites that offered to "ships in 2-4 days" or other questionable practices, and far cheaper than Amazon. But the best news is that the sander arrived, with their "free ground shipping," less than 48 hours after I pulled the trigger on line. CPO will be one of the first places I check in the future for mail order tools.