I have ordered from rmr before and was very happy with the .30 cal. Nosler 175 gr Custom Competition bulk bullets they sent. I also am very happy with some primed Federal .270 WSM "pulled" brass I ordered from them. But I will bet you lunch that the Speer 55gr SP bullets will shoot groups half the size of any open base 55 gr FMJ bullet from RMR or anyone else. Plus it will provide better performance on target than a FMJ bullet. I am all about saving money on components, but cheap generic FMJ bullets are not accurate enough for my purposes. I want decent performance and for the extra $3 in shipping cost ($15 for shipping across the country for 1000 of the Speer bullets, so the total delivered is $84), the Speer are a better deal, at least for me. But if all you want to do is see how fast you can empty magazines and wear out barrels, then by all means, find the cheapest junk bullets available and enjoy.
I just thought I would share what I thought was a great deal on some decent quality bullets that can probably shoot moa, or better, in a good rifle.
And, Paddy, yes, RMR still has some of the Nosler 175 gr HPBT Match bullets for a great price, especially if you order 500 or more.