Relics and Treasure cause insane bills.

[Tigertanium]

I found 5 treasure from the text event from traveling past vines and excavating dig sites which range in value of 8000-10000 simolions (treasure actually has value and isnt just for show, neat), problem is, if you try to display this treasure anywhere or have it in a display case, you will be billed for them and this causes the 700 simoleon bill you get from the grass bills, tree bills, air bills, creatable bills,right to live bills to skyrocket to 10000 simoleons Just for 5 collectables that i got after only 2 adventures to selva-whatever! Why am i billed so much for the treasure I FIND (the fact im billed to no end for the grass and trees I place and every object that i payed full price for is crazy and monarch/dictator dystopia like enough). The bill system ruins the ability to collect and display the treasure you get from doing the stuff the pack adds.

[wa-wa-world]

I feel you, i played some sims in tbe goth mansion a while after the goths had died off and the bills were like 10000 each time.
You could purchase a retail lot and display them there I don't think retail lots affect the bill amounts the SIM supply did this in his laters rags to riches on YouTube.
There is also a reward trait called frugal which reduces the cost of the bills by like 20% and a reward for completing mansion baron is all build mode purchases are refunded slightly at the end of the week which might solve your tree problem

[Playalot]

Welcome to the forum @Tigertanium   
The reason it seems as though you are being billed for the treasure you find is...you are. Bills are calculated as a percentage on the households and lots worth so anything on the lot or in your sims household and personal inventories are taken into that calculation. 

So due to this game play mechanic, if your controlled sim is on a holiday lot or community venue at the time the bills are calculated then it is that lots worth that is taken into consideration. This is a bug but has been there for years. It's always best to be on your sims home lot when bills are calculated which is sometime early Monday am, 4am I think from memory but certainly sometime between Sunday midnight and Monday 6am, in-game time obviously.

I personally like the bills and wish they were more as imo it's too easy to make money in TS4.

[Joria]

Welcome to the forum @Tigertanium   
The reason it seems as though you are being billed for the treasure you find is...you are. Bills are calculated as a percentage on the households and lots worth so anything on the lot or in your sims household and personal inventories are taken into that calculation. 

So due to this game play mechanic, if your controlled sim is on a holiday lot or community venue at the time the bills are calculated then it is that lots worth that is taken into consideration. This is a bug but has been there for years. It's always best to be on your sims home lot when bills are calculated which is sometime early Monday am, 4am I think from memory but certainly sometime between Sunday midnight and Monday 6am, in-game time obviously.

I personally like the bills and wish they were more as imo it's too easy to make money in TS4.

  I disagree!  My bills are making my supposedly rich Sims, (imported Nancy and Geof Landgrab and twerp Malcolm), poverty stricken.  Seems they can't keep anything they are earning no matter how hard they paint, garden, fish, etc. etc. and sell.  Don't think bills were this huge earlier in game.  Is the Frugal reward cumulative? If more than one Sim in a household has it I mean.

[Playalot]

Frugal reward stacks, yes.