John Meyer said he found one on eBay for $105.95 which is an amazing price.

and

it would be great if i could get two cords, one short while using in the mic holder, and one for boom mic operation...

The kit I purchased on eBay included a short and a long cord, although the long cord was not long enough for a boom. However, you can purchase any XLR extender and use that.

I got the $105.95 (I checked my PayPal account just to make sure that was the price -- delivered -- and it was) on eBay by bidding on over a dozen auctions during a two month span of time. Like pjrey, I had a budget and didn't want to go much over that budget. Obviously at this price, I ended up under budget.

The key on eBay is patience. Also check completed auctions to see what previous items have fetched. Finally, don't be tempted to bid on merchandise from low-feedback sellers. It's not worth the hassle. Also, there are some things, such as a camera, that I would never purchase on eBay (although I have sold several cameras for amazing amounts of money).

I also sold a $7,000 car for $14,500 several years ago, and about a year before that purchased a BMW for $6,000 but those are stories for another time ...

Wow, what a diverse set of responses to a seemingly simple inquiry (assuming your mono mic is unbalanced) . . .

JM2c:

For runs >= 15 ft. under any conditions (fluorescents, stage dimmers, RFI, et. al.):

1) Use the shortest run possible of mini shielded to 1/8 TS or TRS (meaning the cord attached to the mic itself);

2) Adapt the above to 1/4 TS or TRS, whichever of the above is applicable;

3) Run into a powered DI (also called a Direct Box) (UltraDI is a low $ example) and BE SURE TO LIFT THE GROUND;

4) Run XLR cable from the DI to the board / cam audio inputs;

5) Live with the slight hiss from the active DI which is essentially preferable to the hum and buzz you will encounter with any other setup (the low $ transformer passives such as Rolls and Hosa introduce THD and lower SNR which are more objectionable at mic level IMO).

Again, just my 2c, and as a result of 30+ years in the biz.

If I'm going for a wireless lavalier microphone, is there a significant advantage of XLR over 3.5mm jack? Since it seems like the big difference would come with long cables.

You have tagged onto a 12 year old thread. Got to be a record of some kind.

Please, start a new thread for your topic, and explain your question thoroughly, i.e., balanced or unbalanced, phantom or not,obviously not full XLR for a lav mic unless you're on a wired broadcast bodypack, do you mean mini XLR, 3.5 mm TRS or TS, etc., etc., ......???

Re-post in the Vegas Pro Audio forum which MV and other expert audio folks read and comment, though basic mic connections and powering requirements (Phantom v. Plug-in) has not changed that much (if at all) in 12 years, so some of the previous comments maybe still be valid