If you use reality as a model, there is a quasi-solution to the equipment vs. tier debate.
In real life, a regular guy off the street is able to purchase any
clubs he wants to, but at retail prices. He can get fitted for custom
clubs if he chooses. He can buy the same clubs as TW if he chooses to
spend the money.
The reason most people don't spend the money for such extravagances is because it's cost prohibitive.
Professional golfers have sponsors who supply them with their equipment; in some cases, even custom-make equipment for them.
Why not unlock all equipment for all players, but tie the price to
tier. Make it cost prohibitive for Amateurs (20,000 credits for a L90
R11 driver, or whatever).
As you progress through the tiers, the equipment becomes cheaper,as
if you were a club pro who might get a 20% discount in the pro shop, or a
Nike Tour pro who can purchase his clubs directly from the manufacturer
at cost. All the way up to PGA Tour pros who pay only shipping and
handling to have the clubs delivered.
People would mostly buy what they can afford. Some would shell out
big bucks at lower tiers for the best equipment, but that would be their
prerogative.
In the end, there would be much more financial incentive to advance.
Gifting would have to be at the recipient's price.