Cashback/Coupon Sites:
Get lower prices even without bulk purchases. Become more price-competitive when using cashback sites (and sometimes coupons). Some have also browser addons/extensions.
Topcashback
Ebates
Befrugal (also has add on extension)
Honey Auto coupon finder with extension
Offers (coupons)
Priceblink (coupons and more)

Gift Cards Services:
If you are a dropshipper contact us for purchasing greatly discounted gift cards from the best marketplaces such as Amazon, Walmart and more.

Credit/Prepaid Cards:
Payoneer MasterCard is ideal for non US citizens that dropship in USA. Some Sites -like Amazon- Don’t accept PayPal.
Wirex Visa has one of the best rates for converting money into BTC! Dropshippers mostly use it for buying discounted gift cards at even more favorable rates.

Books:
E-Commerce The Guerilla Way (Contact us for discount before buying)