A couple of points...
As 3AND2 points out, a whole lot depends on where you are playing. I would agree that $1,500 is probably more than enough if you land in the right spot and get some of the logistics ironed out for you (for instance, several friendly landlords or heaven forbid corporate housing next door to stadium). My point is less about the dollars involved, and more about the stress of having to manage it given all the moving parts (transfers, roommate transfers, lining up off season work, etc). Also, $1,500/mo is not $1,500/mo every month. Maybe six months of MiLB salary, 2 months unpaid during spring training and other downtime and another 4 months hopefully working an off-season job - in that scenario it averages out to $1,250/mo.
As for the tier 2 auto plant two jobs ago, that guy must have a long work history. Assuming 40 hr week, that puts these workers making $8.50/hr - not much higher than minimum wage unless we are talking about 20-30 years ago at which point the numbers are irrelavent to today's discussion. Upside is that they get that salary 12 months out of the year and they know exactly where they are living during those 12 months - kind of simplifies life and makes the money go alot further. If the town has a few such plants, then the workers can in fact go elsewhere if the pay is deemed unfair (MiLB is sort of like a small town with a single mill where everybody has to work - or leave town). Not sure what 1,000 folks were doing for minimum wage at an auto parts supplier, but my experience is the fringe guys might be making minimum (while they sweep the floors) but lots were making 2x that amount (basic machine operators) with the truly skilled folks making 3-4x that amount (know how much a skilled mold maker makes these days?). I personally want to be a unionized longshoreman in LA making $100K+ with aspirations of becoming one of the crane operators possibly making twice that (kind of reminds me of the MLBPA).