Below is a list of parts for the Stealth and GGTS with current and previous prices that these parts have sold for, plus estimates for parts not previously sold separately. Hopefully, this can be used as a strawman to begin pricing the Stealth and GGTS Upgrade parts. That the total price to get to a GGTS is $311.91 and greater than what a complete GGTS is selling for now ($249.99 at COV) is justified by the fact that selling it in parts this way requires more inventory maintenance and storage space on the part of the sellers, plus it includes a part (Brass 2 piece connector/cap) not included with a GGTS today.
GG Stealth
Gold Bottom Cap $29.99
Lower Battery Tube $39.99
Switch Assembly $27.99
Brass 2 piece connector/cap $29.99
Total for Stealth $127.96
GGTS Upgrade
Telescope Tube $37.99
Upper Battery Tube $29.99
Collection Tank Tube $24.00
Collection Tank Bottom $28.00
Connector Insides $13.99
Thread Adapter $15.99
Cap for 901 in brass finish $19.99
Control Ring $14.00
Total for Stealth + Upgrade $311.91
Edit: Added the Control Ring