> LM324N (I can get many for cheap, but it´s not a FET input device...)
LM324 has low enough input current to work in many hi-Z circuits. BUT it has a terrible output stage, deep class B, gross crossover notch distortion. You can design around it, but there are better choices. (324 is a fine amp for many non-signal points.)
LF147/347
LF444
KF347
These are in the same family as the 071. IIRC, the 071 was a breakthrough in minimum die area, most chips per pound of silicon. These others may be more liberal with silicon and thus give more output current or smoother clipping. Or they could now be re-labeled 07x chips: the designs are similar enough that it makes sense to merge them. Juice-up the silicon, use the 07x mask, it might meet 347 specs too.
> they'll even ship overnight for us in the USA for free,
Note: if you register at National (similar sample program) with an EDU email address, they won't give you overnight service. Students with a term-project deadline should not wait to the last minute. However, after promising 2-6 weeks, they actually got samples (requested on an EDU account) from Singapore to eastern USA in about 3 days. So you might get lucky.