What is 'worth' what is something that only you can decide. Having two SE/30s myself, I should not hesitate to pick up another in good condition if only to improve one of those that I already have.
There are dedicated Asanté NICs for each of the SE and SE/30. Look at eBay for MacCon+ ... (three port combinations) and MacCon+ 30iE... (two port combinations), respectively.
SimasiMac is one only of a variety of faults that AIO monochrome compacts may have. Look here for the story.
The SE has limited expansion. The SE/30 is both capable and a remarkable case-in-point of what Apple had developed from simple origins. The 128K is that simple origin, but hardly impressive for doing much at all. Most of the SE/30's potential add-ins are scarce and potentially pricey, but 128MB of RAM and 32-bit operation under System 7.5.x are not hard to achieve.
Even after The Fall, there are still plenty of data to be mined in these Forums about the SE/30. Surfing is barely possible for the SE/30, but only paddling in the shore waves for the SE.
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