Have you looked at steel "T-posts"?

Hi Josko,
It doesn't cost anything for an estimate ,call a local fence company and tell them you would like them to give you an estimate to install galvanized fence poles. It is cheaper than you would expect, and if you don't have the tools and experience to do it yourself, it will actually save you money,to let a professional crew do it.

{{gwi:8596}}

What Jon said.

Try the Fruit and Orchards Forum. What you're describing is a very common trellising technique for brambles, and the experienced growers there should be able to advise you.

If your going to be tighten up the wire and want to avoid a massive post and concrete thing you should google how to brace a corner post T post will not cut it on the ends would work fine for the middle I don't think you would need concrete if it was braced good enough

Dig the holes as deep as you can your rocks might decide that(: then see if you need concrete you don't have to mix it just mix with the back fill dirt make sure to use a tamper bar to beat in and compact the soil around the post after every few inches of fill

Call your local power company if there is one near by and ask about some old cedar poles sometimes they have them a lot of times only the bottoms were creosote treated

You can get fence tightener ratchets at a farm store very cheap to keep your wires nice and tight come to think of it that would be a great place to ask about the fencing too

If your going to be tighten up the wire and want to avoid a massive post and concrete thing you should google how to brace a corner post T post will not cut it on the ends would work fine for the middle I don't think you would need concrete if it was braced good enough

Dig the holes as deep as you can your rocks might decide that(: then see if you need concrete you don't have to mix it just mix with the back fill dirt make sure to use a tamper bar to beat in and compact the soil around the post after every few inches of fill

Call your local power company if there is one near by and ask about some old cedar poles sometimes they have them a lot of times only the bottoms were creosote treated

You can get fence tightener ratchets at a farm store very cheap to keep your wires nice and tight come to think of it that would be a great place to ask about the fencing too

I put in two fence posts for a grape arbor two years ago. It cost me $700---hospital fees, plus materials. Standing on a ladder, I heard me command myself, "Ann, you hit that nail like a man would," right before I landed on the ground with my thumb broken down the middle from tip to first joint.

Lesson #4222

Clint Eastwood as Dirty Harry once said:
"an Ann's got to know her limitations"

Like Jon said.
Get post put down & string 1/8 steel/stainless steel cable across it. Put up ribbon so you can see the cable.