I was concerned about the very same thing, and focused all my efforts on building multi in any way possible. I was fortunate and many opportunities came my way. Before I list these opportunities, I would strongly suggest obtaining your MEI before you buy a block of 100 hours of time. If you're going to be spending that much money, you might as well get another rating to show for it, and in today's market, even the more scarce MEI job is probably easier to find than it used to be.
My multi was built by:
Multi rating-10 hours
MEI rating-5 hours
Corporate flying program at my flight school-30 hours (turbine)
Weather modification-50 hours
Corporate flying internship-150 hours (turbine)
Again, I was pretty lucky, and the biggest opportunities were possible due to connections made through my 141 flight school...but you can see that you might have to do all sorts of off the wall things in order to get that first 100 multi. In the end, it's worth it for the varied experience, and money saved. I didn't do any multi instruction, but wish I would have had the chance...I think it'd be a great way to build experience.