The issue with guys priced at 28-35 in 2RF is that when they perform as hoped and give you 40-45, they still need to be upgraded to a gun sooner rather than later. Buying an underpriced, gun level player at the start saves you a trade, as they can be a keeper for the season, saving approx $150k value of a trade that you can use elsewhere.
If it was that easy to find an under priced gun we would all do it in every position. There simply aren't enough players capable of doing that to warrant not spending trades.
Last year for example
Hooker: You have to go all the way to Mahoney who was the 6th best averaging hooker. His average was 14 points lower than the #1 which is firmly not keeper territory
Prop: Haas was the exception not the rule. Only prop in the top 10 averages to have been "under priced" by 10 points or more was Haas. Every serious team traded in Haas with-in 2 weeks
Second Row: Bateman and Murray the only options here. No one started the year with Bateman(everyone trading him in) and everyone started the year with Murray. No advantage here
Half: Moses the only half to increase average by 10 points and be a keeper. Most had him in time for the run home with very few owning him before the bye rounds
Centre: Bird increased his average by 10+ points, however was in majority of teams by round 2 and had to be traded out
WFB: CNK increased average by 10+ points, was in every serious team
How do you plan to find these under priced gun level players that no one else does?