Commercial SouthBend Range Stove Oven-Needs Replacement Parts-But Super Expensive-what to do?

[jimtmcdaniels]

Hi 
Just looking for Any insight and direction to this situation:

Small commercial kitchen with a non-convection, 36" Wide, 6 stove burners SouthBend Brand Range Oven, Model# 300F that needs some replacement parts because some of the burner's pipes are rusted through.
Also some gas leaks out of the burner knobs(I think that just needs to be taken apart and re-graphite greased). 
SO I see for just one replacement for the rusted burner is $487 on Amazon(had the best price found):

Amazon.com: Southbend Range C50-00006 Stainless Steel Rear Burner : Appliances

Amazon.com: Southbend Range C50-00006 Stainless Steel Rear Burner : Appliances

www.amazon.com

This range has other rusted through parts that need replacing.
These crazy prices are cost prohibitive and makes the purchase of a new range make sense. Especially when I see what looks like a similar size SouthBend range for as low as $2700:
https://www.katom.com/348-S36DNG.html?utm_source=google&utm_medium=cpc&utm_campaign=%5BROI%5D%20Shopping%20-%20PMax%20-%20Push%20Harder%20SKUs&utm_id=17563307644&utm_content=&utm_term=&gad_source=1&gclid=CjwKCAiA9dGqBhAqEiwAmRpTC5r0Sk2TV3a9gQphyAU5t1vd7g73hA1hzlARR3pYLeDuOZM51bxOPxoCweQQAvD_BwE
Yet another similar size SouthBend models are $6000, don't understand why: 
https://www.katom.com/348-4364DNG.html?utm_source=google&utm_medium=cpc&utm_campaign=%5BROI%5D%20Shopping%20-%20PMax%20-%20Push%20Harder%20SKUs&utm_id=17563307644&utm_content=&utm_term=&gad_source=1&gclid=CjwKCAiA9dGqBhAqEiwAmRpTC6fDZOhahtkdX_Ewl6rCqOM8HXgfG6hyjjAd50FTLbuVSSCW8e7FLhoCnpEQAvD_BwE
SouthBend 300F Manual-(Owner/Service/Parts/Schematic Wiring): 
https://static-pt.com/modelManual/SOU-CO-300_spm.pdf?v=1655476559196

Q's:
1. Are the replacement parts prices so high because its an old model(not sure how old) or does SouthBend price Gouge their parts?
2. Should we shop for a new Range instead of replacing parts on this old range?
2a. What Range brands are recommended (for price, reliability, serviceability, parts price/availability?
3. Are we missing something here or not understanding something about this situation?

THANK YOU FOR ANY REPLIES!
Take care

Jim