I personally would put in a few more dollars and buy the originals, but if quality isnt your main concern, then these sites that sells compressed DVD or VHS convert might suit you.
I have friends who bought from here and AngkorDVD.
Their experience from KhmerHut :
1) Like Yak has mentioned, fast shipping
2) Comes with the black rectangular DVD case, if you buy it [white labels]
3) Quality is OK for VHS converted to DVD
AngkorDVD :
1) Shipping took a bit long
2) Horrible quality, but their DVD are digitally printed on....looks nice, superficially.
NOTE: Their experiences with the quality all pertains to Chinese series, therefore, I cant say much about the other dubbed products.
From the ones I've seen of my friends, KhmerHut has way better quality than AngkorDVD, if you must buy from them.