My Mum took up 10m Air rifle at the age of 63 and is using a S400 MPR with the Target rifle sights, it is not going to compete with a top end target rifle on its regulation or trigger but I shot 3P for Sussex about 4years ago and to be honest when I tried it I can honestly say it was me that was not performing not the rifle.
My Mum does have Kurt Thune Jacket (having a Son in the business has gotta have some perks) but no boots or trousers and she comfortably averaging 75+ and still improving so for a sensible starting point I would seriously recommend the S400MPR or look out for a secondhand one. Don't discount single stroke pneumatics still very accurate and around at sensible money.
Hope this helps
David