From Longman Business Dictionary
introductoryin·tro·duc·to·ry /ˌɪntrəˈdʌktəri◂/ adjectiveadj [only before a noun] MARKETING introductory offer/price etc a special low price that is charged for a new product for a limited period of timeIt will normally sell for £12 but as an introductory offer the booklet is available for just £10, until the end of the month.