I started collecting Alien figure hot toys just this year and honestly I LOVE THEM!
Yes, as everyone said they will have deterioration/rubber issues, but honestly it's not so bad that is should scare you away from collecting something you enjoy.
The first hot toy alien I received was dog alien... this is by FAR my favorite alien. He is in EXCELLENT condition with the exception of his snap on leg being a little loose. I paid $200 for him and I felt like that was a good deal. For such a terrible film, this is the best hot toy alien produced to date in my opinion.
Second purchase was a blue warrior alien... he is by far the "coolest looking" alien figure I have, yet he is in pieces (see photo)... I need to mold a leg and two arms. He is really cool and the detail on him is 10X better than the other two alien warrior figures.
My next purchase was the other two warrior aliens who are in PHENOMENAL shape, neither of these have joint issues! The brown ones chest was tore when I purchased it, but a little glue fixed that right up. The standard blue alien warrior is the best (quality) piece I have (he even stands up on his own). I would not say he is as cool looking as the above photo... but with a little detail (cover him in KY jelly "slime") I am sure you can get him to look great.
Lastly I purchased a big chap (who never arrived) :cough: eBay :cough: but it did have noticeable issues, such as a cracked dome and joint problems.
Honestly, if you are going to purchase alien figures do it on the forum and buy them used... In my experience sellers have been so honest and they sell them at a fair price rather than asking high prices on a place like eBay, craigslist, or amazon. I might not have the boxes and they might not be BRAND new, but I am very happy with them!