What zip(s) are you delivering? Beverly Hills or South Central? Greenwich or Bridgeport? Precisely who comprises the audience? HHI of $250K or $25K? What kind of real demand is there for that audience? Are the panels themselves in good shape or are they beat up like most surviving 8s? Are they correct (true) or cross reads? Are there obstructions present? Who are the other sign operators in the space-- bloated stuffed suits or hyper-aggressive local guy-- and what are they charging to reach the exact same audience? Is there another media form in the area considered more dominant? Even though it's said to be "bananas and oranges," what are they charging? (To the local advertiser it's all "money out" so competing media matters more than we OOH guys sometimes like to admit.) All of this criteria is relevant and needs to be considered.
If you're the same person who is looking for construction help in SoCal, and these signs are indeed located in SoCal, then you should be aware that SoCal is already home to the country's largest 8-Sheet plant. Lamar operates approx 3,000 or so 8s in LA County and the OC. Because of that fact, you're already tied (somewhat) to Lamar's pricing philosophy and, as a result, when you talk 8s to an informed buyer, you can't be too far above their general pricing philosophy. Also, you should be aware that 8s aren't very popular with the agency community out there-- they're mostly viewed as an urban buy or, even worse, an unsightly, unnecessary and inefficient relic left over from the days when "big tobacco" used them to penetrate local neighborhoods. Point is, you're prob going to have to do a lot of the heavy lifting with respect to sales with local one-offs and perms (when you can get them). Considering all this, I'd go ahead and mirror the local Lamar rate card and cut deals off that when it makes sense to do so (again, thinking perms)-- single install, can vinyl-wrap entire panel-- as 4W onesies will most likely gap your plant to death.
The good news is, unless you have a ton of these structures and are going to attempt to sell them in showing levels, you'll prob never bump heads with the "Big Green Machine"-- they are best to be avoided in your situation for obv reasons-- unless of course you decide to sell and then they're your 1st call.
Best of luck.