The Serie A is starting a week after most of top European leagues. Is there any big transfer rumours recently? I haven't heard of any... Italian teams are really not very keen on spending a high amount on single player like I said before.
Or maybe Inter doesn't want to go over 40 million euros much.
I don't think they are broke right now.
Maybe they haven't made a big sale in this transfer window. However they made quite much money from the Champions League while reaching the finale...
40m was Inter's offer for Lookman, not Atalanta. Atalanta wanted 55m for Lookman. It's because they're reluctant in selling their player to their rival. In fact, Inter can't afford Atalanta's asking price. The better inter to find Lookman alternative that can fit their budged. 
Or maybe Inter doesn't want to go over 40 million euros much.
I don't think they are broke right now.Maybe they haven't made a big sale in this transfer window. However they made quite much money from the Champions League while reaching the finale...