About 4-5k for all the sound part.

Because i don't know yet how the HVX-200 will be regarding sound recording, i don't know if double recording will be needed (would prefer not)

Lectrosonics is a well respected - here a link to several representative systems on Trew Audio's web site...
http://trewaudio.com/catalog/subcat162.htm

Unless Panasonic has used really poor converters (I doubt it) then the HVX should sound excellent, as it's a PCM format, 48k/16bit.
If you've got that much to spend on a wireless and mics along with your storage for the HVX, you might as well get a high end system from the get-go. Plan on a good hypercardioid, omni lavs, and save the shotgun for last, IMO, unless you're doing a lot of outdoor shooting, in which case a good shotgun is indispensable. Are you a one-man show? Or will you have a boom op? A good boom like the K-Tek Avalon series is wonderful to have, and you'll quickly appreciate it's light weight. They have good shockmounts too.
Get quality cables; Mogami and Canare are two brands hard to beat.
Don't forget some kind of carrying system to pack your audio in.
Small things like furry, rubber bands/hairballs, soft leather, bandaids, etc are all good to carry in case you need to attach cables to other devices.

About boompole... I am not sure if i miss something here. What is the difference between a 100-150$ boom (ex: Gitzo) and a K-Tek that can be 400-600$ ?

Besides weight and variable lenght, what is the differences ?

Audiophiles says that your system is good as your weakest component. I wonder if the HVX200 will be the weakest component in this case. And if so... What difference will it really made v.s. double recording ?

Just asking myself if a 2k mic is not an overkill for this camera's abilities.

Well, I'll put it this way then...I doubt that the Panasonic will be any better or worse than any other DV camcorder, or any other camcorder, period. If you want better conversion than what most camcorders offer, then I'd get a second record device, and plan on syncing it in post.
A 2K mic will generally sound better than a 200.00 mic when plugged into any recording device, regardless of the quality of the device. 48k/16bit is the standard, and while I've not heard the Panny yet, I'd imagine that it's as good as any other cam in it's class. Which means for most things, it will sound great. I wouldn't use it for a rock concert or a symphony, but I'd never use cam audio in those situations anyway.

Regarding the boompole, not only weight, but strength, and quiet. The more expensive poles are much more quiet, better balanced (usually) and can have the cable internalized, which is often a nice time and hassle saver. Additionally, the graphite is much tougher than aluminum, and is more comfortable to hold, IMO.

I'd agree w/ Douglass on all points and add that weight & balance are the major differentials in boom poles, both in performance and price. As the boom operator, would you rather hold a 10 pound weight over your head for 10 minutes, or a 3 pound weight?

The choices for wireless are very broad (and expensive for the good stuff), but you have to know what your application is first. Will you have a sound person or be one-man? Will they be for microphones (how many? Lav, handheld or shotgun?), or for a wireless link from mixer to camera? These decisions can dramatically change your budget and your choice of radios.