Is it even possible for a private individual (not a company) to make one for less than this?
http://www.ebay.co.uk/itm/Gas-Porta...130?pt=LH_DefaultDomain_3&hash=item2c7fb15142
http://www.ebay.co.uk/itm/Gas-Porta...130?pt=LH_DefaultDomain_3&hash=item2c7fb15142