Are there any uniques that are worth doing the vendor recipe for 5 chance orbs? (1 white, 1 magic, 1 rare and 1 unique).
Not really. I don't think there is any unique that's as cheap as 5 chances. Cheapest uniques are the ones that aren't very useful and with low rolls, and even those can be sold for at least 2 alchs (1 alch = 4 chances).
That's based on Hardcore League economy at least, i don't play default league so i don't know are their rates any different.
Yes, there are quite a few uniques that "suck so much" that noone uses them. There are not even some niche builds for most of these, simply because they're just that bad.
Most people do not even bother selling those to others, they just vendor them, but a lot of people still sell them. The introduction of the API, which allows to list items using premium stash tabs, has opened the market up for more people (as most couldn't be bothered using the forums or some 3rd party software in order to sell those cheap uniques).
If you want to find cheap uniques, just visit the inofficial auction house of Path of Exile, select your league & the rarity, and press "Search". It will list ~50ish uniques, starting with the lowest prices. These uniques cost 1x "Orb of Alteration", so you could very well profit using this recipe. Just please, before vendoring it, make sure that you're not vendoring an incredibly good rare.