I recommend just making do with a cheapish sound card or audio interface until you find a good deal on used test equipment (or building your own).
The 8903B is a bit...obsolete, so unless you just want one for fun (who doesn't? =P), I would steer clear unless you find one very cheap. Its residual of ~-95dB THD+N @ 1kHz is in the range of a sound card, so unless that's good enough for your needs then you'll quickly run into its limitations in modern audio.
If you're a bit daring and willing to purchase overseas, look at Yahoo Japan auctions for an old Panasonic or ShibaSoku analyser. IMO they are the only 'old dogs' that hold up today in terms of residual distortion and noise performance. You can sometimes find them for around JPY30,000 before shipping, maybe add 20k yen on top for that, they're usually a bit under 20kg or so.
My Panasonic VP-7722A was around $500 delivered and its residual is ~0.00023% (-112dB) THD+N @ 1kHz, 30kHz BW at a couple of volts or so.
And if that's not quite good enough for you, the 2 decade old ShibaSoku 725B distortion analyser (no built in osc.) can do -116dB THD+N stock and about -120dB with a few easy mods, mainly op amp swaps and a ground rerouting. That's near flagship Audio Precision performance by the way.