would have a chat to stylyn in boronia myself. speak to adam. on site guys could be good or a hack - you really do not know. stylyn I know do good work- part of the reason I refer to them. they do not break things and last I time I was in there he had a E class benz sitting in the shop.
as for price - not bad though I would also look at the GSM pager/tracking option as well. GSX560 (its a DEI product also.) is the part number - autobarn will list it but probably not have it on hand. I have info on it and I'll get it on the shop site shortly when I get a sec.