Well if you have a look on euro car parts at the cost of a lower arm bush and an anti roll bar link your looking at 50 quid for the cheapest complete lower arm. an anti roll bar link is about 15 quid. So a fair price for that repair would be around 65 quid plus no more than an hours labour (and that's working slowly).

As for the welding repair the cost is on labour. Although those holes don't look massive once they start cutting away to find decent metal to weld to that hole could become 4 or 5 times as big so has the potential to be quite a bit of work. I have never had to pay for any welding work to be done so I'm not sure what a fair price is to repair .

P.s the prices above were taken using the reg from the missus's 02 focus