Agreed... EASILY done for under $15K. (We're doing a mobile oven build our own and it's coming in way less than $15K with trailer and everything.) Here's the ovens I researched when preparing for our selection, and there's probably more out there. You just have to gauge on your own in terms of what you want to do with the oven (commercial or just at home), just pizzas, etc.
A couple notes:
1. These are pricing at the time I researched (dec 2012) and dont' include tax or delivery fees. Study up on your state taxes and your dealer's state taxes so you know whether you should be charged sales tax.
2. Some of these are DIY kits, others are full assembled. They all have multiple options, so you'll need to dig into each one a bit more.
$1,395 Round Boy Oven http://www.roundboyovens.com/
$1,799 Los Angeles Oven Works LA 800-516-5716 email@example.com http://www.losangelesovenworks.com/ovens/siena-model-60-wood-burning-oven.html
$1,800 Raul's Ovens Seattle, WA 360-850-8340 firstname.lastname@example.org
$2,450 Bel Forno Pizza Ovens (888) 902-9387 email@example.com http://www.belforno.com/purchase-wood-fired-ovens
$2,599 Wildwood 323.255.6578 x 104 firstname.lastname@example.org http://www.wildwoodovens.com/
$2,942 Maine Wood Heat (Le Panyol Model 83) Maine 207-474-7465 Jake@mainewoodheat.com https://mainewoodheat.com/wood-fired-ovens/wood-burning-brick-ovens/le-panyol-model-83/
$3,200 Forno Classico http://www.fornoclassico.com/
$3,350 Breadstone Ovens http://www.breadstoneovens.com/
$4,640 Outdoor Pizza Oven (Batali 750) Chicago 800.256.5534 email@example.com http://www.theoutdoorpizzaoven.com/countertop-pizza-ovens.html
$8,800 Earthstone Model 90 PA or 90 PAGW 800.840.4915 firstname.lastname@example.org http://www.earthstoneovens.com/resoven_modular.shtml
$9,900 Rocky Mountain Woodfired Oven (with Trailer) http://www.rockymountainwoodfireovens.com/?trailer=igloo-trailer
$12,999 Tailgater (Fornobravo, and UL approved) Boulder, Colorado 303-652-7378 email@example.com http://mobilewoodfiredpizzaovens.com/mobile-pizza-ovens/wood-fire-oven-catalog/
I didn't include anything above $15K due to your restriction, but if you want the others, just let me know.
Also, I have no masonry skills, but if you have some basic tools (hammer, drill, sawzall or saw, wire cutters etc.) and are willing to be patient and research on this forum as well as Youtube, you'll be surprised how much you can learn to do yourself in building the oven. In this day and age, there are infinite resources for you to learn from.
Key tip I'm going to pass on to you if you DIY: Make sure you were sleeves when you work with insulation. While I work pants, shoes, goggles, gloves, respirators for protection, my forearms and cheeks (face cheeks you dirty birds) are feeling like they're being bitten over and over again thanks to not properly preparing for working insulation in advance.... Ouch. =(