Historically the amount of required ME time varied between 50-500.
When hiring is slow or non-existent (like right now) and a lot of pilots are competing the published mins are typically 200+ ME but actual competitive mins to get hired are like 300-500+. Nobody expects you to buy all that time, you need to get a job as ab MEI or in 135.
When hiring demand is high, regionals will lower ME mins to 100-200, some as low as 50 and will actually hire people with only the minimum. Some bottom feeders even hired those with only a ME rating and the 10-15 hours it took to get it.
However..due to the colgan crash last year congress is trying to make airlines (regionals specifically) place more emphasis on ME time. I would suspect (and hope) that no airline will ever again hire with less than 100-200 ME.
If you are in the training pipeline, I would look ahead to MEI employment opportunities. Keep in mind that schools usually prefer to hire their own grads first, so you probably want to do your training at a school which 1) does ME training and 2) will hire you as a CFI, with the potential to upgrade to MEI eventually.
Unfortunately insurance often dictates that MEI's have 25-100 ME hours as well, so be sure you understand the schools policy on that. You might have to buy some ME time just to get an MEI job.