Since it's a limited edition, signed and dated, it would be worth more than a standard Helmstetter cue. There is some collector/player following on these older Helmstetter cues. I would guess an average price for it would be $500 to $600 or so.
Stick it on ebay. Set the opening bid at $1 with no reserve, and let the ebay community (which is comprised of a lot of cue buyers) decide what it is worth. I've been happily suprised doing this with expensive items before, and only one time extremely distraught (took a $2000 loss, but I refused to end the auction early). It is only WORTH what you can sell it for.
Experience tells me that you will get around $300 plus or minus on ebay for it. its a nice cue but not realy a collectors item or a shooters cue. it falls more in the catagory of a "cool if the price is right cue." and as an adams fan, I started collecting them because they are generaly realy quite affordable, and yet pretty cool at that. A cue is worth exactly what some one will pay you for it. I just wish any one of my cues was worth what the blue book of pool cues says its worth!... Maybe someday.( not to get to far off topic), but did any one else expect more from the 3rd edition b.b.o.p.c.after so called cue experts took on the project? ... Its not real expensive for what it costs, but there isnt much new work and NO REAL WORLD adjustments to speak of on so many fantasy values. I wish i could get $ 1500 for a hoppe cue tha was produced non stop in a factory for forty or more years! lol Have A Great AMERICAN INDEPENDENCE DAY!!!!!