It took me ages to get some of the sizes I use at good prices. 6000 6001 6201 are all easy to come by in SKF or INA/FAG however 6900 6901 6902 etc are about £7 to £9 each.
About the same price as 6800 and 6802 bearings, however you can feel the difference when you run the good bearings.
I do a kit for the hustler for £35 jap bearings in the main pivot and INA in the rocker pivots etc.
Weldtite grease is OK, you can get it from chain reaction + a mini grease gun for £10. I tested it and it did reasonably well but not as good as quite a few other greases.
As for the bearings off ebay, they won't last all that long. 12 to 18 months would be my guess. You can't remove cheapo bearings seals without damaging them.
Some wont even last that long, you simply have to offset the cost of the bearings with how long it takes to strip and service the frame. I can't be bothered changing my bearings every couple of years. So I run japanese and INA or SKF. I get them at good prices so I might as well use them.
Well I've finished my dinner and I'm off to finish my frankenstien downhill bike! it's made of anything I can lay my hands on.