Good fencing isn't cheap wherever you get it from - cheapest is usually those thin, interwoven lathe panels from places like B & Q or Wickes. Might last 3 years, maybe a bit longer. On the other hand, pressure treated featheredge, with a concrete gravel board at the bottom and pressure treated posts should last 10 years without the need for creosote, then another ten years or more if kept treated regularly. Fencing really is an area where you get what you pay for.

You've not filled in any details on your profile so no-one will be able to give you any pointers really, we'd need know what location you're in to be able to help more.
Fencing panels vary in price though and, as with most things, you get what you pay for.
I'd get 4 different quotes from fencing companies in your area and take it from there.
'Bite the bullet' and see it as an investment - after all, it's your home and our home is our castle.

Although I agree with Bamboo that more expensive panels will last longer I have supplied and fixed many fences over the years and my own fence built using 6 by 6 cheap panels from B&Q has lasted 11 years and is still going strong and hasn't even been creosoted yet!

My best advice is don't buy cheap fence posts. The reason why most fences fail is because the posts rot at ground level. I've examined many broken posts and just underground and just above ground they're as good as new but in the area at ground level where they get wet and don't dry out properly this is where they rot. ,

The post above ground stays dry so is not liable to rot and underground there is little air so they rot only slowly .I would suggest you buy either pressure treated 3 by 3 or preferably 4 by 4 wooden posts or preferably concrete posts which will last a life time.

They are heavier to erect but have slots into which the panels fit so you won't need the U shaped fixing pieces that cost quite a bit.

If the fence panels are kept slightly above ground level they will dry out quickly after rain will not rot for a long time and even cheap ones will last ages..

I don't know how old you are or if you're good at DIY but fencing is quite straightforward and there are some good DIY guides on the Web. For 6 by 6 posts you will need a helper as in even the slightest breeze one person cannot hold them still.

If you think you can go the DIY route I'd be happy to talk you through it.

The 'Waveney' (todays price about £20 for the 6ft by 6ft) fencing down the sides of my garden has lasted 16 years, some is now in need of replacing but all the posts are still in place and in good condition. The Close board fencing across the back of my garden is the same age and in very good condition, all we will do this year is replace the wooden gravel board at the bottom as they are beginning to go. I think modern wood fencing is Tanalized and never needs treating?
I was recently quoted £230 plus vat thats about £270 to supply and replace just 4 pieces of Waveney (at £22 each) by Tate Fencing. I thought this was excessive and now plan to do it myself. But I would not attempt any posts. One other thing is to make sure that 'Lap' fencing is in a complete frame so it lasts

Many fencing companies give totally silly quotes. I've seen as much as £80 per panel fitted for simple cheap fence panels.

So that's at least £60 per panel labour. A good two man fencing team should be able to fit at least one panel an hour and if it's a simple run one panel every 30 minutes is perfectly possible. That is very good money! Ofcourse there is the cost of concreting in the posts and the cost of the post itself to consider and if they have to take down and remove an old fence then this all adds time .

Why not buy the materials seperately and then get a labour only quote?

My quote above was from a well established firm who obviously didnt want the job! Anchorman. But getting the materials separately from the labour I have found difficult in several things as the buying of materials makes them a bigger profit on the overall Job. I was recently quoted £100 to supply a new replacement for an outside light. £50 for the light and £50 for labour. I decline and went and bought the light my self for £30 now I cannot find an electrician to come and put it up!

Why not ring some firms and ask if they'll put up your fence panels? ( do this before you buy them so you're not stuck with them if they won't!)

You could also ask local handymen if they're interested.

I used to do handyman work and that's when I did the fencing.