Well, the Blue Book suggests a value of $800 in Excellent Plus and $675 in Excellent. I think the system was very pricey in the day. I don't recall actual new retail prices but $3,000- $4,000 is probably in the ballpark. Clearly there were at least two fellas in the auction you observed that reeeeally wanted one again. It would be nice to get your bass paired with the GR-33B synthesizer again. I bet the price on the intact unit far exceeds the value of purchasing the guitar and synth separately.
BTW, I think the bass was made by Ibanez for Roland; I'm not positive on that though. Fuzzy memories