The average value of an antique Royal typewriter depends on numerous factors, but runs between $100 and $400 in cases of rare or excellent condition pieces. A typewriter that is in mint condition is going to sell for far more than a typewriter that is in poor condition.
Where a collector finds a Royal typewriter can also influence the price. A piece found at an antique shop will likely have a higher price tag than one found at a flea market or yard sale. The pieces found at antique shops may also come with warranties to cover repairs or guarantees of authentication.