I topped out at level 28 at the very end of the game. All star systems and side quests were fully explored at 100% and finished, so there is a definite limit on the amount of XP and money attainable in the galaxy.
However, I imported a level 50 instead of 60 so that might have something to do with it.
I got the level bonus from importing a lvl 50 character, I scanned all planets, did all N7 missions, all side-missions, and the main mission. At the end, I had maxed Paragon and was lvl 28. How someone got to lvl 30 in one playthrough is amazing to be honest.
i made a [new] shepard (long service medal), so i starded at lvl 1, then got everything 100%(all star systems) and i was lvl 29 when i starded the suicide mission. and i got lvl 30 when i killed eyeball paul
if u dont have long service medal then its not posible to get a lvl 30, i at least didn't make it to lvl 30 w/ my imported me1 lvl 56 char.