The biggest risk to a person who self sponsors a type rating with no guarantee of a job afterwards is the lack of recency.
A type rating is just the beginning. If you don't keep current on it then the skills you acquired rapidly fade away, esp if you are not flying any thing. If you don't have experience to fall back on then getting back up to speed in a hurry can be quite difficult.
No one is providing you with a job if you do a rating. You have to get that yourself.
easyJet won't take low houred on type self sponsored people without running them through their own TRSS. I dare say they will still need a few 737 folk as the A319 is being introduced to the fleet. With Mytravel not being the strongest there's still a lot of jet qualified and current pilots out there.
So, before shelling out the cash. Do your own research, don't just read what people are posting on these forums.
Ask yourself, how am I going to keep current if I don't get a job?
(Note, you are no longer "current" after 3 months)
Tootling around VFR in a cherokee is fun but not that good for your scan.
What does this type rating provider actually provide? Just the rating? Line training? Who are they teamed up with?
Study the market carefully.
Is there a risk that if my potential (eg turboprop) employer finds out I have a jet rating that I may well lose that opportunity because they fear (rightly or wrongly) you'll be off to a jet operator in a short time?
In some cases, you could well be better off using the money to help finance yourself looking for work in (eg) Africa where you'll get some great experience and move on quickly to better equipment.
Sometimes you have to think outside the loop. Life's an adventure, enjoy the trip.
As has been said, it's a gamble. Play with only what you can afford to lose.
You don't buy a house or a car without doing a lot of checking, apply the same to a rating or even the licence itself.
Caveat Emptor.