As far as the used Field box being a good price @ $125 but worth $250?? I don't know what all he has in that used Field box that makes it worth $250 but you can get a couple different types of complete combos Field box, starter, Battery, Power panel, fuel pump etc. for around $119 NEW! Tower also allways has some kind of discounts going on that will absorb the cost of shipping. Here are a couple you can look at to see how they compare with whatever it is that he wants $125 for used.
http://www2.towerhobbies.com/cgi-bin...&I=LXL419&P=ML
http://www2.towerhobbies.com/cgi-bin/wti0161p?&I=LZ0600
Those are just a couple of examples, there are more to choose from. Personally I wanted the Great Planes Master Caddy, but I wanted the Hobbico starter, so I kind of mixed & matched what I wanted, still came out to less than that used box you're talking about.
As for the glue, I watched my Dad build very fine flying planes with wood glue for years before there was any CA. Of course he had to use hot-fuelproof dope too. These days some guys use all three, Wood, CA & Epoxy. I'll leave it to the guys with the building experience to tell you what is best to use where.