Wouldn't such prices vary widely not only on time and geography but other circumstances? American would sell arms to say, Egypt at a very different rate then say, France. It isn't like going to Walmart and buying some tanks, many times they are part of larger diplomatic and commercial treaties, right?
It's almost impossible to get a definitive price for such things, not just for these reasons but also because it depends what's included. A country purchasing (say) combat aircraft might choose to
- Have the aircraft delivered to them, or to have their pilots fly them over.
- Have their personnel trained in the country that builds the aircraft, have them trained at home, hope the manuals cover it all, or something else.
- Buy spare aircraft so they can fix some, use some for training, and maybe crash a few.
- Buy spare parts to fix the ones that need it.
- Buy the manuals that tell the personnel how to use the spare parts.
- Buy weapons for them to use, in varying quantities from 'none at all' to 'far too many'.
- Get the facilities to operate them constructed as part of the contract.
Often, when someone's comparing a 'super cheap bargain price' that one country has paid to a 'ludicrous rip-off price' paid by another, the difference is likely to be that the former has got as few 'extras' as possible, while the latter has got lots of spares, training, and so forth. It's fairly normal, for instance, for export orders to include only one warload of ammunition. A first-rate power is likely to want enough ammunition and spares for an extended period of combat - perhaps up to a month, depending on the timeframe.
Following that up, is the lucrative maintenance contract. Some companies/countries are well known for having really cheap up-front costs, but charging a fortune for maintenance and spare parts. Or for cunningly making the guns with slightly different specifications than everyone else, so you can only buy their ammunition at prices well above the rate for the standard type. Of course, everyone is playing these games, just in different ways.
That's before brown paper envelopes stuffed with cash, political horse-trading, and questions over development costs enter the discussion.