I would say Tikka are the reason the trade in semi custom rifles has declined. Tikka T3X actions are silky smooth out of the box and as already mentioned, they are known to be accurate with there being limited to nil reports of a tikka not shooting well. They are also very weather resistant. Even the blued model I owned showed no signs of corrosion after bad weather. There are a multitude of after market parts to customise the fit and handling. Unless you have specific needs, which as a recreational hunter, I don’t envisage there being anything that the basic factory rifle doesn’t offer.
Secondhand rifles do offer good value, it’s a buyers market. However, there is risk involved when you don’t know what to look for. Barrels are like tyres and wear out with use. Unfortunately unlike modern tyres they don’t come with wear markers. Even with a borescope it’s not an accurate science.
Package deals can look enticing with the apparent savings. But does the package really include what you want. Be mindful that the less expensive Steiner scopes don’t use European glass. There is an advantage at first and last light when using European glass, this being when 99% of deer are shot. As the saying goes, if you can’t see it you can’t shoot it.
Calibre wise there is plenty of history on here discussing the merits of one over another. My personal opinion, deer aren’t armour plated and then you put a hole in the right place they will die. Any legal calibre is the right one and will get the job done.
The reality is, buying the rifle is the cheap part of stalking. Unfortunately there is huge over demand for opportunities with most, but not all, land occupied by a sitting stalker. So be prepared to pay for leases or stalking opportunities.
Have fun with whatever you end up purchasing and practice.