don't bother with a second hand screen, cos the scrappie will charge you 40-60 for one then you have to have it professionally fitted as it's a bonded screen, which is gonna cost you another 30-40, don't think you can fit it with a tube of silicone, the glue used for bonding glass is a polyurethane and with be eaten away by silicone plus silicone isn't strong enough to give the stiffness whe dry( a windscreen can form upto 40% of the structure of the vehicle) and in the event of a roll over,won't prevent the roof from crushing your head!!!
these are a simple screen to fit for someone that knows what they're doing, the best thing to do is ring around as many windscreen companies as possible and battle them against each other, as the trade is very quiet at the moment you'll get it down to somewhere around £80.