I would suggest living within your means, that is, get the loan without help from your parents. If you get a bigger loan on account of their co-signing, what would happen if you lost your job? For that matter, what would happen if you decided you wanted to quit your job for some reason (having kids would be one example)? If your loan is bigger than you can afford with one income, then you will both be tied to your jobs for the duration of the mortgage.
I don't know if the 150,000 loan would get you anything in your area. In some places you could get an actual house for that (not the nicest one, of course), in other places, you could at least get a condo for that. That's how most of us start, I think, with a "starter" home, then move up as our financial situation improves. I will say, it's tremendously fulfilling to build a life together with your own resources.