Ooh, I really really want a Tentipi but can't afford one, and don't have the drying storage space 
I think you have to trust the company you buy from though, and a lack of reviews can be very telling.
why not consider running a business like this yourself?
I always admire people who run their own business, it's such a huge amount of work and stress, I think sometimes as well, especially with direct sales things people don't actually look at the figures ie
How many sales will you need to make to recoup initial investment? - you also obviously need to factor the cost of sales, and any other ongoing costs.
How many sales will you need to make to make x amount of profit?
I think sometimes people just look at the retail cost of what they are selling and forget that they will have to buy that item + all the overheads which may well not leave that much profit.