Oh, yeah, you bought a boost (step-up) converter. I may do a review of those, if there is interest.

Did you buy the buck converters for you test for $7-$8 each on Amazon? You can find all of the buck converters in Chinese shops too 1 2(5 pieces, a cheaper single one could probably be found too) 3 4

Looks like the Amazon shops also bought them in China, the names (Drok, Smakn, Ailavi) are just the names of the corresponding Amazon seller. I also have one of the USB buck converters which you called Ailavi, it works much better than the boost converter (which is sold on Amazon too). I just don't know where I put it last so I could check if it reaches the same efficiency as the module which you have. So if you want to test boost converters the ones which are shipped from China are most likely the same but much cheaper. There are also other ones available than the 40cent blue one

PS: How do you like your Rigol o-scope? I've been thinking of getting one.

If you don't want to buy a used scope or can't find used scopes for a reasonable price the DS1054 (with the 100MHz 'hack') is probably still the best way to go for a <$1000 scope. I have mine for about a year now and I can recommend it, only the FFT is crappy.

EDIT: Looks like this guy did a review of your 40-cent chinese made boost converter: http://www.rei-labs.net/cheap-ebay-boost-module-comparison-and-performances-5v-from-one-or-two-batteries/ -- Looks as bad as you discovered.

He tested it up to 200mA, that's a output current where it can (almost) reach the 5V, but these blue boost ones are sold being sold with the promise to be capable of up to 600mA at the output. But since it doesn't even work at 500mA it's not useful to charge most devices at all or they will charge really slowly, maybe ok if one needs 5V for a micro controller or so with a smaller current.