If it's close, drive out and take a look. Take a ball peen hammer along and see how it feels. Let it fall from about 10 inches from the face of the anvil without any force. Let your wrist pivot free. The hammer should bounce up about 1/3 or more of the distance it dropped. Also, here's a great little bit on information from anvilfire that can help out:
The Steel Ball Test:
A test inspired by Robert Bastow when he commented on anvilfire by saying, "You could bounce a 1" steel ball off the monitor!"
Obtain a steel ball bearing ball (1/2" (13mm) to 1"(25mm)) in diameter. Drop the ball 10" onto the face of the anvil. On a really hard anvil the ball will bounce about 75-90% of the distance dropped.
We tested a number of anvils and other items in several shops one weekend and here are the results. We have continued adding to the list.
93% - Peddinghaus 165# Forged Steel Anvil
85-90% - KOHLSWA 325# Swedish Cast Steel Anvil 55-57 HRC
90% - 70 pound "Smith Steel Casting" farrier's anvil
85% - Black Granite Surface Plate 8" thick
80-85% - High quality wrought anvils - Hay-Budden & Peter Wright (average)
65% - OLD 18th Century hornless anvil with 5th foot - about 75 pounds.
58% - Soft cast steel 50Kg Russian anvil (average test).
55% - Worn out old anvil, looks like an old Mouse Hole circa 1800
50% - Rail road rail - short section of modern 150# section
35% - Colonial Anvil 125# missing horn and worn out!
30% - Monel Boat Shafting (50/50 Cr/Ni)
25% - 2024-T4 Aluminium (hard, aircraft type)
25% - Annealed SAE 4140
20-25% - Ductile Iron Swage block
20% - A-36 Structural steel plate 8" thick
15% - Aged Concrete (Smooth)
15% - Milling machine Table (Mehanite)
10% - Imported Cast Iron ASO's or doorstops.
5-10% - Massive cast iron weld platen
5% - Red oak log (endgrain)
If it is in good shape and hard, snap it up quick! Even if there is a very slight bow in the face or some mild wear, it can be resurfaced by any well equipped machine shop. $1.50 a pound is a good price if in good shape.
--nathan