My 17 month old is around 30lbs and is in size 5 diapers. I too, find that the noName diapers are just fine, as long as they are changed every few hours, after one pee. Although almost every morning she is wet right through her jammies, I think this is because she is a milk queen and sleeps 12-14 hours at night. I wouldnt expect much more from a brand name diaper.
I think it is wrong to think that a parent is purpousefully sending the "el cheapo" diapers to you just for spite, but maybe because she has just bought a different brand. I buy whatever is cheapest. I care for 7 kids under 3 so whatever works will do just fine. I have yet to find a "cheap" diaper, and I have tried all the brands.
My only problem with the store brand variety is that you need to buy a size larger than the child would normally wear.