That black case in my picture, I bought from Goodwilll for pretty cheap. I had to replace a few side glass panels, hardware and I completely refinished my self. It used to be a light blonde colori. I made it antique black.
I would also check Craigslist. search for display case or curio.
Be careful of the plastic degradation of the figures.
Can you go into detail about this?
The plastic gets soft and sticky. Also look out for the brown mould spots.
http://www.action-figure-resource.com/sticky-plastiaction-figures.html
Thank you. The brown spotting cant be cleaned? Ive seen some figures on ebay with that but still got a high price
I read that you use vinegar but just not sure
To the best of my knowledge it cannot be cleaned as it is not some type of external dirt or blemish but rather deterioration of the plastic itself from within. Some people call it āplastic rotā. Some figures are more prone to this especially, Bengali, his hammer and Pumyra. 
And as Mark pointed out, figures kept tightly sealed in a hot area do tend to get sticky to the touch. They might even start smelling. Also try to keep your collection away from direct sunlight as the UV rays can cause and accelerate the yellowing of MOC bubbles as well as discoloration of some parts.
I kept my entire loose figure collection in a plastic box in a store room not near heat and when I went to have a look at them I noticed the plastic had gone extremely sticky and some of the limbs even a bit soft. I did notice a few figures had developed rot spots.
I have to research the spotting more. I actually found a Bengali with hammer original and it seems that theres a few spots on a leg and one arm.
Be careful because like Wilycub said as far as I know the damage is irreversible and will only get worse over time.
The sticky plastic and the rot was the cause of me having to sell my entire collection. :(:cry
Iām looking around and most of the Bengali figures I see so far either has light spotting as I mentioned or chipped paint
If you have a bit of experience with a brush, touching up the paint chips should be easy enough.
I would be very tempted to try and buy my collection back again, but my collection of loose complete (except for 2 weapons) action figures sold for just slightly short of Ā£500 in September 2014, but I really donāt know if I could get them back for that price.
Iām not experienced with a brush by no means.
Acrylic paints arenāt to hard to mix to the correct colours.
Got to be honest. Itās a little discouraging to see all the issues Iām beginning to see with a few figures. I know Iām new to collecting figures. I just got to find a happy medium I suppose. Lol
The rules of collecting are basically the same no matter what you buy. The longer you wait, the more expensive and ārareā items become. However that being said, only pay for an item what you want to pay.
There will always be people who will advertise a price based on the perceived emotional value of a toy far beyond reason and hold out for that $700, even if the toy normally sells for $400 but if you are patient you will eventually find someone who is moving an old collection, or just wants to pass the joy onto someone else at a fair price.
As other have mentioned, if you get figures that are not pristine on the cheap- a little semi gloss Tamiya will fix them right up! There are all kinds of toy repair videos on youtube. I recently learned that a hydrogen peroxide bath in the sunlight sucks tarnish out of plastic without damaging it. Amaaaaaaaaaaaaaaaaaaaaaaaaaaaaazing!
Thank you
Youād probably only get a fraction of your collection back for Ā£500. A loose complete Driller would set you back around Ā£150. Loose complete Bengali, Pumyra and Lynx-O each go for around Ā£80 +. Or you can just buy a Tongue-a-saurus for Ā£500 and call it a day! 
Just be careful when buying and donāt rush into buying the first one you see as sometimes you can end up with a better one in better condition for less money.
Maybe a few of the main cast figures.
Yea I have to be patient. I know Iām going to make a mistake here and there.