Hi,
I would not worry too much about your age being against you - 33 is pushing it a bit but there is so much more you can bring to the class (particularly given your current background in consulting) that other "younger" members of the cohort will not be able to bring in. It is also true, the schools you have mentioned (Insead and IMD mainly) are more "tolerant" of age compared to most of the US B schools. I personally think that having age on your side, you will be able to take so much out of the program as well.
Having said that, there are a few things I think you could also consider:
1. Do you really want to go for a full time program or a part time, executive program?
2. The career choice, however is slightly more trickier - even if you are able to get into a B School of your choice, a subsequent career move is more challenging. Moving from SC/procurement consulting to strategy consulting (there are very few pure strat. consulting firms) might not necessarily be that tough for you without an MBA - why don't you try getting into Strategy&Ops in Accenture, big 4 accounting firms or get in an internal Strategy role (for a large corporate)? Maybe start with strategic sourcing and then move into Business Development and then into Strategy and Products?

Hope this helps

You can still get into INSEAD at 33. However, are you sure you want to do the full time program? Would an executive program fit you better? Something to look into, but a big part of school is the network you will develop. If the average age of your classmates is much lower than your's you will be at different points in your career and your network might not be as helpful.