How much should a person spend to get a decent power conditioner?

Lots of good advice in there.  I am familiar with Furman, my power conditioning strip is a Furman digital 10 outlet.  I like the idea of something under 5 bills for effective results because that's basically what I have.  I am not familiar with wall warts, unless that is a familiar term for the pucks.  I have already added ground rods outside, one at the AC unit and another at the shop.  The transformer is probably close to 20 years old, so it's a concern, at least to some degree.  Perhaps, the Brick Wall iin front of the Furman and we'll call it good?

if you hope a furman will fix cable rfi and hum you are on wrong track...

that is where cheaters may help but you MUST keep a component grounded w three prong - typically the preamp....

a wall wart is a digital switching power supply, i guess you refer to them as a puck...
anyway, well documented and measurable the trash they dump into power line as well as RFI generated....

cleaning that up = good

if possible get a linear power supply...

seperate circuits also help a lot....ideal is three w digital, low level analogue and power amp all on dedicated lines...

inhave four w DAC olso on a dedicated line...
snakeoil for sure....

a wall wart is a digital switching power supply,

They're used to power laptops and tablets, also small components like some DACs and streamers. Their design produces dirty power to the audio device and allows noise to flow back down the AC line and contaminate other components. 
To eliminate this noise, a linear power supply (which contains no switching circuitry) should be used.
Many of the audio manufacturers offer an LPS for their devices, plus there are many very affordable aftermarket units on Ebay.

wisciman, daisy chaining 2 power conditioners is not an ideal way to lower the noise floor. You'll be running your components thru extra circuitry which will probably limit dynamics.

It would be preferable to use one conditioner for your analogue components and another one for digital devices.