I'd agree with Michigan Mama that how you wash (and probably dry) them would impact how long they last. I don't have experience with the brands you mentioned, though.
I have MEOS that I bought when ds was 14 mos old and then used until he was somewhere around 33 mos, so 19 mos there. I've used them with dd for probably 7 or so months...so a little over two years I guess. I have a few where the terry fabric on the inside is thin, but no holes and the elastic is in really good shape.
I've bleached them on occasion, wash on hot, and use the dryer in the winter (line dry in the spring/summer/fall as weather permits), though. On the other hand I know of someone who had MEOS and they were incredibly worn by the time the first child was done with them. So I suppose some variability is to be expected.
I'm not sure mine will survive through the third child, though.

That's probably not very helpful, though. In the end I'd agree with iowaorganic - go with some prefolds to get you through to the end. It'd certainly be much cheaper and if you're doing the GCDH this year you can 10% off at all the sponsors (plus addt'l individual deals) that'd make even that a bit cheaper.
For a more expensive option, but still relatively inexpensive, that's sort of a prefold/fitted hybrid you could always go with something like
Daddy Flats which again is a GCDH sponsor.
ETA: On the ones where the elastic is shot, if that's the only issue why not see about having the elastic replaced? There's a
tutorial over here on how to do it if it's a "casing style". She had mentioned putting on up for replacing elastic if it's the "gathered" type, but I didn't see a posting for that. She talks about doing diaper repairs on her blog so if you aren't comfortable doing it yourself, you could always contact her directly to see if she could be of service.
Another elastic replacing tutorial
here.
Oh, and I've also read that you can probably find someone to replace the elastic in diapers over at DS.