For some reason this has never been popular, but ThePuck has just posted a tute on building a mod that uses 4 x stock AAA rechargeables of the NiMH type. He calls it, um... the Puck.
It needs two back-to-back boxes as one is filled by the batts. He runs a 901 but there is no reason it won't work with a 510, in fact @ 4.8 volts or thereabouts to start, dropping to maybe 4.3 volts or so, it looks absolutely perfect for a stock 510 atty.
The full tute is in this thread:
www.e-cigarette-forum.com/forum/battery-mods/105465-now-puck-cheap-parts-easy.html
It's a good one with nice pix. He doesn't sell them so you'll have to build it, but learning basic soldering isn't too hard. Or you could PM him and ask if he'll 'assist' you...
This looks to be a good idea. The theory is (which is why maybe nobody did this before?), that the Li-ion batts we normally use have a flatter discharge voltage, the NiMH have a steep voltage drop, also a memory issue. However he says this hasn't been an issue for him.
I'd say it's worth trying, especially if you like the idea of a 4.5 volt vape (which is going to be very popular on stock 510s IMO), with cheap, easily-sourced batts. Also it comes out as a small-format boxmod, which many will like. It's sure going to get less looks on the train to work than a Chuck + AFS
