Google: JEDEC bakeout
Sub 100°C the bakeout times can be *very* long e.g. 10 days for a 4.5mm thick package at 90°C & maintained <5% RH. At 125°C, the max bakeout time is a far more reasonable 48H.
A DIY oven for the purpose of baking out small quantities of loose parts could be as simple as a 40W incandescent light bulb in a high temperature holder mounted in a tin can with a ring of holes round the edge of the base for airflow, then a shallow aluminum tray, to hold the chips suspended above the bulb, with space for air circulation at the edge, and a bonded on thermocouple for temperature control, a lid with a vent to control the air-flow due to convection, and a programmable temperature controller capable of following a temperature profile, controlling the bulb power via a TRIAC. PID proportional control would be preferable. The can exterior and the lid should be thermally insulated.
If the components cant withstand a 125°C bakeout, then you'd need something fancier, with a drier on its incoming air. For components of uncertain provenance, I would suggest holding at 95°C long enough to significantly reduce the moisture level before the 125°C bakeout.