for a trade printer i would say its down to the resolution you want & vinyl type/performance. some large format printers have low resolution & look crap up close. e.g. “superwidegraphics.com” £17 a square metre (price includes vinyl) from them is good but only if your prints are large and are being viewed from a minimum of 10-15 feet away.
there are a good few trade suppliers on the go with similar prices, but remember and take that into account.
if the prints are onto large flat panels then any decent make of vinyl will do, if you want to increase the prints life to the max i would advise to have it lamintated.
if speaking to people like racoon, explain exactly what you want from your image. where its going, for how long, will it be veiwed up close as people walk by or from afar? im sure they will cator your needs.
at the end of the day, your prints maybe much more than £17 but you will get what your after.
on the other hand if this is for something like a vinyl image up on the side of a building or carpark etc then the £17 prints will do just dandy. 😉