Beginning later this month, 20-year retail veteran Andrew Arcovio hopes to go on-line with Send-a-Book, a computerized network that operates like a bookish FTD, linking member bookstores nationwide to fulfill a customer's order. Customers dial the Devon, Pa., start-up's 800 number to locate the nearest member store, where they order their desired book either by phone or in person. The originating store then calls Send-a-Book, which locates the member store nearest the recipient. The fulfilling store gift wraps and delivers the book, and keeps 80% of the book's list price plus the $5 handling-and-delivery fee. The originating store receives 15% of the list price, and Send-a-Book 5%. Membership costs $35 per month and is open to both chains and indepen dents. Because Send-a-Book provides members with "a guaranteed sale," Arcovio feels the network can particularly benefit small specialty stores. Send-a-Book currently employs 10 sales reps around the country to open and ser vice member accounts, and an in-house staff of 8. Arcovio conservatively projects he'll have 500 members doing a minimum of 400 orders (minimum order: $20) during his first year.