I've never had a bad experience with Drop. The only issues I have is their shipping and prices. (but the price on these caps seems great to me)
Their shipping methods here in the US are incredibly slow. I mean, once something actually ships, it usually takes 7-10 business days to show up. Depending on what day that ships, it can take two weeks to get my stuff! I can get USPS from one coast to the other in 2-3 days usually. I don't understand why they move so slowly.
Also, most of the things they sell can be found for the same price or sometimes cheaper on sites like amazon or ebay or aliexpress, and you don't have to wait months like on drop. I'm assuming the "deals" they offer come into play more with international buyers in those cases, who can take advantage of better shipping rates?