Health Cabin sells parts in bulk on a sliding scale. You pay normal retail until you order 20 of an item and the price begins to go down.
If you want 50 attys, it'll be in the first bulk range. If you order 51, it'll slide into the next bracket below.
Around 1000 units and you need to contact them directly for a quote.
If you wanna do that, contact Amy from Health Cabin and ask for the wholesaler's price list.
The only downside to this is Customs, since the parts come directly from China. If it's seized by customs, you just lost 50 attys.