Used Linn sondek lp12 worth?

Hi guys,

It's been a lont time since I've last posted....and I would seriously need your help.

Well, for the first time of my life, I have decided to get into vinyls (and therefore consider myself a newbie) and might have an opportunity to get my hands on a used TT.

I could get a Linn sondek lp12 circa 1988 from one of my best friend's mother. It has the Valhalla power supply, a SME Series III tonearm and an AKG P8ES Supernova VDH II S  moving magnet cartridge.

The lp12 has received both a Trampoline 2 and cirkus upgrades in 2015 from a Linn dealer. Also the cartridge has been rebuilt with a new suspension and a new VDH shibata stylus, again in late 2015.

Overall condition is very very good.

My friend's mother is nearing 80 years-old and is struggling with serious health issues. She has therefore decided to part with (among other things) her lp12. No shipping would be needed as she lives 30 minutes from my place. I could pick her TT up personally. 

She wants 900$ for it. 

Now, I have absolutely NO IDEA what her TT is worth?

I have tried to search the Web on various audio sites to get an idea about the lp12's prices BUT they really are all over the place !!!

Should I go for it at 900$ and take the plunge ? Am I getting ripped off or is it the other way around (I wouldn't want to take advantage of her either)?

I want both her and me to settle for a fair price. What would be a reasonable $$ settlement? 

Hoping for your advices

Thank you very much for your help.

Sincere regards
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I'm going to be very frank with you. If you don't buy it, you're nuts. If you pay less than what granny wants, you're a dick (particularly in view of circumstances). That TT is worth way the hell more than the price being asked. Just do it. It's a killer piece.

I would think the arm and cart alone are worth the price. As far as the LP12, it may require a tuneup as the LP12 does on occasion. But even with a good tune up, 900.00 is a very fair price for both of you. At her asking price if she sold here on Audiogon, she would have to package it properly and ship it. At 900.00 it goes bye bye and she is done, free to buy what ever she wants. If she doesn't have the original packing that can cost 75.00 shipped to her alone plus trying to make it all fit in the box. Good luck, the LP12 is a wonderful table set up properly and can be upgraded beyond most budgets. I sold mine and do miss the musical warmth it can deliver.
Thanks to all of you guys for the quick responses. It really seems like a  a "no brainer" kind of deal.

lindisfarne, the main purpose for asking those of you in the knows was exactly to avoid being "nuts" or a "dick" !!! ;-) Wanted a fair deal for both parties. Now, according to fellows comments, price seems to be very good but still fair.

Finally, the only remaining unanswered question is to know wheter or not I could get a better TT for this kind of money (or say up to 1100-1200$). If you gents could answer the latter, I'd be a very happy camper indeed.

Thanks in advance