for the Space Marines to get free transports, you have to pack in a lot of units, you need a full company, so two Battle Demi Companies, with everything else bare bones, you're talking 1250 points just to get the 2 Devestator squads with Gravs in drop pods, if you want anything else that's not 5 man tactical squads or attack bikes the points will add up very quickly. Hell, play 1200 point games and its not even possible.