We rarely use R&D in our games because of the cost and random nature of developing a tech.
We have tried out various ideas to get tech in the game. I especially want to use HBG’s tech units in our games (Me262 Jet Fighters, I-400 Super Subs, etc.)
We even use the tech tokens from Anniversary so if you don’t get a breakthrough, you can keep the token and roll again next round. You don’t simply lose that money. Even with that, while playing we find that we just don’t want to spend the money on tech rolls. We always seem to need more combat units and don’t want to leave an area short.
Separating the techs by making certain techs more expensive than others is a good idea to cut down the randomness. For example: Heavy Bombers or Long Range Aircraft should cost more than War Bonds or Paratroopers because they obviously have a greater affect on the game.
Oh yeah, speaking of Heavy Bombers, we use a house rule where Heavy Bombers roll 2 dice and keep the results of both.
We have tried giving free tech rolls but haven’t found a good balance yet. In one game, we made it too easy and EVERYONE ended up with tech items. Kind of defeated the purpose. In another game, we made it a little too hard and we were back to nobody having techs.
Lately, we haven’t been able to play as often as we used to (work, family, etc.) so when we do play, we tend to play a more basic game that we are all familiar with and don’t try entering new things, which in our case includes techs.