330i's pricing vary wildly - Not hard to find a reasonable sedan around the same price as an 130i auto, ive seen a few sell in 2k range lately (usually rough but same as any old car that cheap). 130's may have lower average mileage but they are all older cars now so condition is really what clued people are looking at. Significantly lower performance is debatable - brand new vs brand new i dont believe it would be a huge gap on a track, but even if it were its going to be much less in average driving. E46's are way more DIY friendly\modifiable with a massive community which is what makes them great.
3.0L Z4's always seemed overpriced to me and limited practicality, always heaps of sale.