I don't believe eBay have a courier-type service to us, but Banggood has a pretty good selection of electronic modules. Do you need boost or buck modules? Or both? Start here and look around:Does eBay have something equivalent to this??
Banggood not ideal for electronic components.. (DC-DC converter)..
If you want to buy cheap dc converter buck, choose dc converter buck from banggood.com. It endeavors to provide the products that you want, offering the best bang for your buck. Whatever dc converter buck styles you want, can be easily bought here.