lots of choices...ScanMaster is great tool, however, it would be dedicated to the Buick. Scanmaster cost is around $250 + tax + shipping.
for me, I did not want or need a dedicated scan tool fixed about the instrument cluster on a street car that would never be raced competitively.
so, I choose a scan tool that would read the OBD-1 data from our turbo Buicks as well as reading other mfgr OBD-1 data, OBD-II data, and later CAN stuff for any car. mind you this was some 20 years ago when I choose the AutoXray EZ-SCAN 5000 and EZ-SCAN 6000 tools for this purpose. They appear on ebay here and there and are great scan tools for less than $200. original price when new was $400+ for the EZ-SCAN 5000 and $550+ for the EZ-SCAN 6000. both tools have nice freeze frame data recording for analysis.
Actron bought AutoXray in 2008 and promptly discontinued the AutoXray products so as not to compete with their current scantools. As such, the Bosch-Actron CP9690 scan tool became what I recommended for a multipurpose scan tool for both the buick and your other daily driver vehicles. it has nice recording / graphing capabilities which makes it sort of a "powerlogger" device.
today, it seems the CP9690 is out of stock at both Jegs and Summit.
there are some good listings on ebay for the EZ-SCAN 6000 and 5000. one link below for the 6000 looks like a really good buy. I have no association with any of these products. data sheet and user manual for the AutoXray 5000 / 6000 scan tools are attached so you can compare your choices and what each does.
nice AutoXray EZ-SCAN 6000 on ebay now =>
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Bosch-Actron CP9690 scan tool at summit link =>
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