Pergola repair suggestions, on the cheap.

[Rorschach]

I visited an elderly friend of my mothers today, her husband died and his workshop (shed) needed some clearing and she offered me the tools. Very kind of her, she of course had no idea what was in there, mostly it was cheapy poundland type tools that were all rusted up but there were one of two useful items and plenty of nails and screws as you would expect, I was doing her a favour by clearing it out really and I tried to offer money but she wouldn't take it.
By way of payment I have told her I will go around and help tidy up the shed properly, hoover it out, remove junk etc and generally be helpful in lieu of payment for the tools.
While I was there though she told me the pergola her husband made was getting a bit loose in the ground. He built it 20-30 years ago and the main posts (4x4 buried in the ground) are rotting at the bottom as you might expect. From about a foot up from the ground the posts are still solid and the rest of the pergola is in very good condition but the most important part is that it is covered in trailing roses that her husband planted, they both loved roses and the garden is full of them.
If I can I would like to help stabilise the pergola for her so that she can continue to enjoy it safely for the rest of her years she is in her 70's so if the life of the pergola could be extended another 10-20 years that would be plenty.
Does anyone have any ideas how I can cheaply, and without damaging the current structure, re-inforce the posts?

My initial thoughts were to dig down either side of the main posts and bury a piece of 2x4 each side or maybe just one side of the post, extending up about 3ft past the rotted area, and then lag bolt the 2x4 to the main 4x4 post and hopefully, while maybe not the prettiest repair it would hold the posts steady for at least another decade. Anyone got any other ideas?

Oh and any repairs need to be cheap since I cannot afford too much money for materials and she certainly cannot.

[Someone-Else]

Sounds like a plan, but I would suggest you dig down beside one post first to see what is there. I am thinking it may be concrete, in which case you would have to remove that before you could put in a post next to it.

[Rorschach]

Sounds like a plan, but I would suggest you dig down beside one post first to see what is there. I am thinking it may be concrete, in which case you would have to remove that before you could put in a post next to it.

Initial investigations did not show concrete (at least not in the first couple of inchesof soil) and she thought they were just buried right into the ground a few feet. Before doing anything though I will check for concrete. I guess if there is concrete that will really scupper the plans.

[big-all]

this one picked at random
http://www.scaffolding-direct.co.uk/met ... spike.aspx
this type is designed to find its way between the post that remains and the concrete its in
prop up the structure chop the old post at concrete level fully remove the post
drive into position
feed a new post in from above
secure new post in the old post position at the top
if the post is badly rotten in the concrete you could remove what you can fill with dry postcrete then bang in the repair spike affix the post then wet

[ayjay]

On the cheap: find an old metal bed frame - chop the angle iron up into suitable lengths and beat them in next to the posts - bolt/screw together.