Asterisk-mart sells 48 sheets for $4. If you go macro first with regular TP and thus use one wipe per session, folding it over as needed for coverage, let's say you max out at $6 worth of wipes for a month because you don't know you're sensitive to gluten yet and you also wipe up some cat vomit every few days.
That's still only $72 a year, man.
Now: How many bathrooms does your house have? Let's say you have two bathrooms and want to use both. $500 on toilet seats? Better hope you're not a 300 pounder who rocks back and forth a bit when he's in a hurry, cuz you don't get Apple Care with those seats I'll bet.
If you travel every once in a while, or need to use bathrooms at work, there's that factor too.
You didn't include the regular TP. With a bidet or washlet, you'll need a lot less of that, too.
> $500 on toilet seats?
There are much cheaper options available. As another commenter mentioned, you can get a non-electrical attachment for as little as $30.
For example:
http://www.amazon.com/Luxe-Bidet-Neo-110-Non-Electric/dp/B00...
Edit: Also, you were comparing the price for upgrading two toilets with the wet wipes expenses for a single person.
If I catch someone traipsing to the restroom with a box of wet wipes under their arm, they're not going to make it without being made fun of. Sorry, princess, but your anus isn't really all that special.
That's even true if you use regular toilet paper, because you'll need a lot less of that.