Post in the wanted section somebody on here will prob be able to help you out, that or type discovery breaking/rear screen into ebay, try to get one that's already been tinted, mine got bust by the Mrs when she didn't put something far enough into the boot and slammed it, I got one from bump on here , already tinted and with the rubber all for £30 delivered, took about an hour to fit it.
To get my original tinted by a professional tinter friend of mine it cost me £30.
You can buy pre cut tints off eBay (avoid cheap they turn purple over time, buy double pigmented).
Easy enough to do yourself if you have the patience, just make sure it's prepped well and as clean as poss, I've done em before with weak fairy liquid solution in a spray bottle, a plastic spatula with a teatowel wrapped around it , a credit card and a stanley blade.
A friend of mine puts the tint on (in the bath!) Before fitting the glass and swears by this method