I think the scale of the 'Exposure' does matter here (please don't just downvote, hear me out).
Exposure = Advertisement, right? Wouldn't you pay for advertisement?
Now, if you invest very little for advertisement, you might get very little in return.
Say, your investment is doing a free 'exposure' gig for a return of 20-30 potential customers. This might not be equitable to your time/equipment/team/etc.
Now, in the example of doing exposure for a well known show (I don't watch any reality shows, btw), then:
1) Getting exposure to millions of people
2) Gaining the ability to say you worked on 'x' show
3) Your pictures being out there
4) How about other negotiated perks for doing this? (Right to use and ownership of material, being most important).
5 days of this investment does sound like a lot of money, but I believe the real question is: "Does my investment have the potential to yield to not only cover initial costs, but turn a profit?"
If the answer is 'yes', go for it. If it is 'no', then decline. I truly believe this is a business decision.
I am not saying people should be working for free. I truly think your time and resources are highly valuable. What I'm saying is that 'free' might not always mean 'no return on investment'.