Opening Record Store

Looking for advice from my fellow audiogoners...I have the potential to move into a store front that is already being operated as a record store (lps only) and become the new shop proprieter/owner. The owner has offered me the space (rediculously cheap rent) in a good area of town. He has had his store for about 5 years now and has a steady customer base. He will be taking all of his inventory and record storage bins that were in the store.He has a web site set up already and signs out front indicating the name of the shop...I plan on rebranding the shop with name change and interior upgrades. It is not a large space maybe 800-1000 square feet. I have a rather large inventory of my own so my up front investment of vinyl would be minimal. The owner wants me to buy him out..basically give cash in return for his customer base and the potential to get my hands on pretty good collections. I am trying to come up with a fair valuation of something like this and I am looking for advice..What do you think something like this is worth? Thank you in advance.
You've already heard a great deal of great advice here - I'd add a couple of elements:

1.) What do you really want to do this potential business for?  What's your motivation?  If you're highly motivated, upfront money may seem different now than later.  Likewise, a passing hobby is far different than feeding yourself or a family - cheap rent or otherwise.  

2.) What are your differentiators?  You can throw a rock and hit an online version of a record store, and everyone is popping up a record store in every antique mall in the country.  What's going to make you different?

3.) Selling 'your' inventory is more difficult than selling 'inventory.'  'Your inventory' has a personal attachment to it that could negatively impact you very quickly.  

4.) What's the real time commitment?  How much is your actual 'profit'  after you factor in all the real time you'll have to invest?  Then take that and compare it to the answer to #1.

5.) The immediate value of the previous owner's business is slight more than zero but far less than you're been talking about paying for it.  The previous owner is looking for a number to get out of the shackles of that business, while there's virtually no upside for you.  If you can't negotiate a non-compete then perhaps you can work on a draw or something where you are splitting the costs over time in order to minimize your overall financial risk.  Actual partnership where you both share in the business with you taking on some sweat equity while not having to fork over the entire nut.  If he wants out, that shouldn't be an issue for him unless he's looking to either pay off something or finance something else.  If he's not willing to discuss it, then you know what you're truly walking into.

6.) Virtually every used record store that I know also deals in new product in order to get people in the store - especially 'new' customers.  That's a significant upfront investment that can go stale as distributors wont give you terms until you've established a track record with them.  That can be crippling if you're forced to buy $10K of product but only sell 30% of it within any reasonable time period.  

Again, not to be disrespectful.  Best of luck with it.
Warning Wil Robinson!

I did something similar years ago in the Midwest  and it didn’t end well for me.  What reason did the seller give for wanting out? Is this 800 square feet of space rent free?
Rebranding costs money. A new sign alone can cost a fortune and then there’s advertising, where the Sky’s the limit.
How much will insurance cost?
Will you need a safe?
Will you need an alarm system?
Will you need a cash register?
Will you need a computer, Printer and backup hard drive?
Do you have 80-100hours a week to put into the place?
Have you talked to an accountant? Do you have another source of income?
Will you be able to establish credit with Venders?

 I can go on.

What ever you do, all the best of luck!

LOTS of good advice on here...after 40 years I could definitely help (on the phone)
get in touch... 
Check out YouTube I have seen several successful record store owners do videos on what it takes to be successful. Check out Spinmeroundstore and noble records to start.
Some really great, no nonsense advice from the posters here...I have nothing to add.