Not at all affiliated with this seller, but saw this on the MoHPC Forums, and thought I'd share.
http://www.amazon.com/HP-HP50G-50g-Graphing-Calculator/dp/B000GTPRPS/
$50 for a new 50g. That's $1 per g. Meanwhile, $85's the cheapest you can get an 83+ for, and really it's far more fair to use the 89Ti, which is $130+. (Some things the 89Ti does better (screen resolution, ease of use out of the box), some things the 50g does better (build quality, CPU speed, having RPN as an option if that's your thing, the sheer level of programmability (there's even an assembler that supports both Saturn and ARM assembly, in the OS), expansion (SD card slot)).)
I wonder if this means bad things for the 50g, though... but it's still listed on the HP site at $129.
Also, looks like the 39gs is cheap: http://www.amazon.com/HP-39GS-HP39GS-Graphing-Calculator/dp/B000JEP19W/ (This one actually is discontinued, so it really is clearing out old stock.)
But, really, if you're gonna do that, just buy a 50g (or, if you insist on HP's classroom-oriented UI, just buy a Prime, as it's the successor to the 38/39/40 line). The only reason to get a 39gs over the 50g or Prime is that it doesn't have a CAS, and is therefore ACT-legal (after the IR port is taped over), whereas the 50g and Prime are specifically named as banned on the ACT.
http://www.amazon.com/HP-HP50G-50g-Graphing-Calculator/dp/B000GTPRPS/
$50 for a new 50g. That's $1 per g. Meanwhile, $85's the cheapest you can get an 83+ for, and really it's far more fair to use the 89Ti, which is $130+. (Some things the 89Ti does better (screen resolution, ease of use out of the box), some things the 50g does better (build quality, CPU speed, having RPN as an option if that's your thing, the sheer level of programmability (there's even an assembler that supports both Saturn and ARM assembly, in the OS), expansion (SD card slot)).)
I wonder if this means bad things for the 50g, though... but it's still listed on the HP site at $129.
Also, looks like the 39gs is cheap: http://www.amazon.com/HP-39GS-HP39GS-Graphing-Calculator/dp/B000JEP19W/ (This one actually is discontinued, so it really is clearing out old stock.)
But, really, if you're gonna do that, just buy a 50g (or, if you insist on HP's classroom-oriented UI, just buy a Prime, as it's the successor to the 38/39/40 line). The only reason to get a 39gs over the 50g or Prime is that it doesn't have a CAS, and is therefore ACT-legal (after the IR port is taped over), whereas the 50g and Prime are specifically named as banned on the ACT.