I traded an 1/18 M1 (Regazzoni) and paid a little more to get the other from a collector friend. I only traded the M1 (comes in dealer box) because I already have another complete set (Piquet and Regazzoni). The E30 Warsteiner DTMs by Autoart is the holy grail of all 1/18 E30s. If you see one btw 200-250 USD, that's considered a good price. E-bay is your best bet to get them, both are discontinued now.
Autoart is very detailed in scaledown, fit/finish, decal print quality than Minichamps. I treated all my die-cast to Zymol Carbon/Creme before storing them, and my E39 only gets cheap Meguiars...ha..ha.