I guess we are both missing the point DaveyF.
In many cases "BASIC TTs" don't require chasis/motor changes nor extremely expensive "upgrades" because they are simply good enough to compete with the best of the best.
Your point, start with an entry level LP12 and build all the way up as funds allow by changing parts to optimize sound. We can both agree that this is a very expensive upgradeable path; from $4,200.00 to $20,000.00+
My point, start with something more substantial than an already quite expensive entry level turntable like the Majik LP12 and optimize sound by changing ancillary equipment such as tonearm, cart, external power supply, etc.
Not many manufacturers offer an upgradeable path like Linn. However, they do offer different models with noticeable cost effective improvements moving up the line.
Rega for example:
Compare the entry level RP3 to the top of the line RP10. Similar in many ways but EVERY component is vastly improved moving up the line; upgraded plinth, sub-platter, platter, feet, pulley, belt, power supply, tonearm, etc.
From $895.00 to $5,995.00
Don't get me wrong Daveyf, I have always praised the Sondek LP12 because it is a darn good turntable. Still considered one of the top turntables by many audiophiles. Ranked Stereophile Class A analog component.
What I cannot do is justify spending $20,000.00+ on a Sondek LP12 when I could buy a state of the art turntable for a fraction of the cost.
Anyway YMMV.