for foreign aid why not make it stack. if the sender has one then its +50% if both have one then its +100% or maybe multiply and +125%...suffice to say some larger number is appropriate if both nations have it, then it could stay at its higher price. This should also be applied to TROOP aid. sending such small numbers of soldiers is useless to large nations but if it could be increased by say 5x for 1 wonder and 10x for 2 wonders then sending 20k troops would actually be enought to bail someone out of a bad spot. perhaps smaller values if those are too big. 2.5x and 5.0x
with regard to having +250 spies. How about just a spy effectiveness bonus instead. 25% or so, either to total spy strength or just the spies themselves. This means that we dont have to buy so many of the lil-buggers, it ammounts to nearly the same thing in the end. another alternative to this would be something like a pernant +x to spy strength of the nation, it would have to be weaker than 250 i think though since these spies cant be killed.