For domestic shipping, is USPS always cheaper than UPS, FedEx, DHL and other companies?
I plan on shipping items of various sizes and weights. I don't need fast shipping. What's important is price. I want to ship the items as cheap as possible. All shipping is domestic (within USA).
Below are some of the items. Note that each line break denotes a separate shipment
> 1 can of pop
> A letter-sized (8.5 x 11) piece of paper that cannot be crushed or folded
> A T-shirt
> A small keychain about 3 ounces and the size of one's thumb
> An object about the weight and size of a Mag-lite flashlight that takes 4 D batteries (and battery weight included)
My untested theory is that USPS is always cheapest. Can experienced shippers/mailers here chime in?
Or perhaps there's a company that ships cheaper than USPS, FedEx, DHL and UPS. Please share your knowledge.