Self sealing bags (Sandwich / Ziplok style) and a texta pen - I know its already been said but they are GOLD
Also score some 20 litre drums and cut them in half.
Get or make a bench and fit it with a good quality second hand vyce. Second hand will get you a Dawn or Record not some Chinese crap.
Angle aluminium soft jaws for the vyce and use them on just about everything you are gripping !
Dial indicator and magnetic base S/H Mercer, Mitutoyo Starrett. Handy for wheel truing, crank and gear shaft end float
Where possible buy good second hand tools with a decent brand name - Stahlwille, Snap-on, Bluepoint even good old Sidcrome and Kincrome etc rather than flea market shitters etc, most of my kit is based on good second hand purchases and I rarely buy new except for special tools and then go for quality eg Sykes-Pickavant bearing pullers (never had one break)
Oh yeah, and a 35 tonne press