Soon, I should have in my possession a Colt AR15 SP1 which, according to the serial number (24XXX), was supposedly manufactured in 1973.  It's been fired in its lifetime, but looked, last time I saw it, in pretty good condition, overall.  It has all original parts, so far as I can tell, one Colt 30rnd magazine, A1 sights, bayonet lug, trap door stock, bird cage flash hider, no forward assist, bolt and carrier, and the black web sling.  I think there's even one of those green cloth, Viet Nam-era magazine bandoleers in the stock, even though they have almost no value on their own.

I'm not a collector in the investment sense, so it's likely I'll be seeking a new home for it.  Besides, I have some bills to pay like most folks.  That being so, how does one fairly and accurately value this rifle?  I've seen prices vary wildly on the Internet and even this board.

It is worth what someone will pay for it. Not trying to be a smart@ss. I just bought a 78 vintage LINB for $850.00. He had it listed for over 1k, but had been sitting on it for almost 2 months and had dropped his price down. The ones that actually sell, go for around $800-$1000 for a standard SP-1 rifle, SP-1 carbines are around $1000-$1200. Don't take my word for it, go to Gunsamerica or Gunbroker and look at their prices.

Good luck with your sale if you decide to sell,
CJ

A dealer locally here in Minnesota has a 1972(210xxx serial#) vintage SP-1 CAR, NIB for $1299. Awesome rifle, I am still trying to decide if I will buy that or a new 6920. Wish I could afford both, but can't this time around. it seems like he has had the 72 vintage for awhile now, so maybe I will make him an offer in a few weeks if it is still available and see if he will take less for it then to try and clear his inventory.