Can anyone direct me towards a dealer who does consignment sales on custom bikes?

Depends on bike, but South Sound BMW does for high end bikes. Read, BMW, Ducati etc.
Quite a few consignment car lots do also.

Sell it yourself and make more money?

Try selling it yourself first.

You'll take a real beating selling it through any of the bike shops I know of.

Consignment means them paying you as little as possible so they can make a decent profit and have it gone ASAP.

Tacoma V-Twin
1310 S 56th St, Tacoma, WA 98408
(253) 472-2209
https://goo.gl/maps/JqrmE6GRxz32

What kind of bike?

It's some kind of custom built chopper, with a racing engine. It isn't mine, and although I've got a build sheet available, I still don't know what all of it means. It's going to take a professional to market and sell this thing. I'm just collecting contacts for her to look at options.

I don't even know what to call this.

Call it uncomfortable

Chopper. Springer front, hardtail? Can't tell from pic.
S&S engine?

Find it's niche....

It was special for some reason.

Either the builder, the engine, the style, the year....SOMETHING made it valuable when it was built....

Find it's niche, research it, and then sell it where it's niche matters to somebody.

No different than a gun, a car, a knife.......

List the build sheet,components and builder matter.Rotthweiler mc in Bremerton is an option as they build custom bikes.Stay away from Harley dealers.

It's been listed for sale for months now. Including here on WAguns. The honest truth is that my girlfriend (the owner) is gonna give this thing back to the bank pretty soon, with nothing to show for the $1000's she's already put into it. I dunno what she paid for it originally, but it's last appraisal was $29,000. While it's been sitting in storage for 2 years, she's paid it down to $23,000, and would take less than what she owes to get it off her hands. It's a crippling debt for her...

2001 Covington cycle city
Custom paint by Jim Parrish out of Tacoma
Patrick racing 113 ci, 135 hp
Compufire ignition, billeted 3" belt drive, 6-speed baker transmission, scorpion clutch, twin 41 mikuni carb.

Whatever all that means. lol

Hate to be the bearer of bad news but exotic choppers have gone the way of the dodo bird over the last few years.
Appraisals are only good for the insurance.
Real life, you'll have to take what you can get.
The bottom fell out from under HD and in turn, they are dragging down used bike sales.
I have a friend that can't even give away a CVO full bagger from Harley. Should be worth $12,000. It's listed at $9000 with zero interest.
In reality there is only one month left to sell the good stuff. Then it goes into next spring hoping for a little more $$$ but by then, it's another year older.

Way overpriced for a 16 year old out of favor chopper unfortunately.