Can somebody recommend a DVD player with USB port to play videof files in AVI and MP4 and MKV

Not sure about MKV, but Pioneer have been selling USB equipped DVD players for around a decade that could play back MP3, AVI/DivX and JPG slideshows. I remember buying one in BK back in the early 2000's for around 2K Baht.

I don't keep up with DVD players, but assume it's going to be pretty standard feature...

Yep - here's one for 1200 Baht: http://piyanas.com/shopping/productdetail.php?cat=124.171&id=1775〈=th no mention of MKV though - if your MKV's are HD, you'd need a Bluray player (or just a recent TV with USB) to play them back anyway - a DVD player won't cut it for HD content.

Toting around films on a flash drive is no longer necessary. Get your viewing device internet enabled and stream it from the source with Plex or XMBC.

LG blu-ray players are not bad for playing files from USB. I have a BD550 that plays most things I throw at it, but it's quite old now. You should be able to pick up a more recent model for less than ฿2,000 I would have thought. As for internet enabled viewing devices - if you're planning on streaming content, you will probably have to use an Ethernet cable, as 1080p files with a decent bit-rate will not play smoothly over most WiFi connections.

I have never seen a "DVD" player that will play MKV files and I dont think there is such a thing available , if there is it is the first I have heard about it .
What you want and which is pretty much the same difference is a Bluray Player .
A Bluray player can play your DVD + CD + MKV + MP3 + MP4 + just about any other format that you can throw at it . You can put the files on a thumb drive or a portable hard drive or a CD or a blank DVD , some of the new blurays you can stream and network files from your computer as well .
When you go to buy the bluray player , bring the storage device that you plan to use as your source and test it to make sure that it plays .
DO NOT TAKE THE SALESMAN'S WORD FOR IT THAT IT WILL PLAY THE FILE THAT YOU WANT TO PLAY . TEST IT TO MAKE SURE .

I have seen Samsung bluray players on sale for as low as 1500 baht that will do the job . I would go with a Samsung if you can find one for a good price , good luck !

Any cheap and nasty DVD player from Makro, Tesco, Big C etc. will pay .AVI files. Unlikely you'll get one that plays MKV files.

Bizarrely, the more ''recognized'' brands often won't be able to do this!

Have a DVD Player in my bedroom that cost 590 Baht, plays all my downloaded torrent files in AVI format no problem.

Take a usb with you, loaded with a few files to try the various formats

Do not rely on sales assistants to know what can be played.