Solder balls for reballing a BGA

I need to reball some BGAs with Pb37/Sn63 solder balls. I need
about 10,000 balls. Does anyone know where I can buy them? I
found a few places selling lead-free solder balls, and a few places
that sell solder balls by the millions, and several manufacturers
that don't sell direct. But I can't find anyplace to buy a small
qty (~10k) of PbSn solder balls. Thanks for any info.

Some of the BGAs are 1mm pitch, but most are 0.5mm. So
I need two sizes of balls.

Btw, I have never actually reballed a BGA before, so if anyone
has any pointers about good techniques, let me know. I am
going to practice on the cheaper chips till I figure out what
I am doing.

-bob
.