If you are looking at the timeshare resale market, the purchase prices are pretty competitive and inviting. You still need to know that you'll have no problem paying fees in the future for exchanges or maintenance. What works for each of us is different.
Now, comparing to stock investments...I guess the prices would be good but the return on your investment will not come back in the form of money. The return will be in the quality vacations that you have and share with others.