I have a friend who's dad owns an Archer that be built a lot of his time in. When he got to college he had private, instrument and a couple hundred hours. Once he got his CFI he taught like one student per semester or something, but a majority of his time was built in his dad's Archer. Last summer he bought a block of multi time, and did the safety pilot time split thing. He graduated this last December and then he got hired on as an FO doing 135 cargo ops in January. I'm guessing he built 400-500 or so hours in his dad's plane plus like the 50 hours he got splitting time. I doubt the 75-100ish hours he got as a part-time instructor gave him that much of an edge. His family would go on long cross countries several times a year, like flying from St Louis to California, Florida, etc, and so I know he had quite a bit of cross country and actual instrument for being a pilot with like 800 hours TT. Maybe the cargo place thought he had a quite a bit of 'quality' time compared to other applicants with similar times.

I know someone else who bought a 150 to do his training in and build hours. He got his commercial last summer and is still in the phase of building time, but he was able to get a traffic watch job for a few hours a week because he met their TT minimum. The last time I talked to him he was around 650 hours and applying at grand canyon tour companies trying to get a tour gig for this spring/summer since he now meets the 135 VFR mins and is hoping to go to the airlines after a summer of doing tours (or a similar job).

I know this doesn't quite answer your question, but the time built in their own planes put them on the fast-track to getting a flying job. Both of them ended up with their part-time jobs just because they were in the right place at the right time, with the right amount of hours, not really because they were looking. I would think once they hit the 1000-1500 TT and 100 multi mark (less if hiring picks up) they will have no trouble getting hired at an airline.

If anything, buying your own time will put you ahead of all of the other wet commercials/CFIs sitting at 250ish hours when applying for traditional time-building jobs, and you can fly in your off-time to build time even faster. When most people are low time CFI's scraping by to find students and get a few hours here and there, you'll be racking up hours in your own plane. Also, if you're looking to skip flight instructing altogether, this would likely allow you to do that.

IMO, there will always be some people that look down on building your own time. But there are people that look down on certain other types of time too, like banner towing, flying jumpers, etc. If worse comes to worse, you should be able to find a job doing something that will act as a stepping stone to the airlines, and having the hours that you bought will help you get that.