Well mom this is an unusual one for a first post. we are a hobby machinist community but we can certainly help. I moved this post here so it would get better /proper attention.
6" vernier calipers are all but obsolete and hens teeth. check with the instructor and see if you really need verniers .
my suggestion is get a decent name brand of dial calipers on the used market.
digital are nice but the good ones are more expensive and you need batteries.
One inch micrometers the same thing good used. and get one that reads ten thousandths.
Three brands to look for: Starrett my favorite, Brown and Sharp. or Mitutoyo.
if you want new: Fowler or pec good but not top brands more value priced.
this is a dial caliper on sale for $29.95 new
http://www.use-enco.com/CGI/INSRIT?PMAKA=890-9373&PMPXNO=4617819&PARTPG=INLMK32
$29.54 for the Mics
http://www.use-enco.com/CGI/INSRIT?PARTPG=INLMKD&PMPXNO=16720828&PMAKA=619-3106
I am a USAF trained machinist and own use a varity of brands and price points of these tools . I have not used fowler much but believe them to be good bang for the buck.
Enco normally has a free shipping promo code to save you shipping cost . I can not find the September one maybe someone can post it for you.
So here is an option for you $60 for IMHO decent new stuff.
these are basic machinist measuring tools.
Machinists take care of there tools so used is an option. shop owned tools tend to be less cared for and may have more wear or they may be on the auction block because they failed calibration inspection so buyer beware.
Tin