Some nice road bikes at reasonable prices
Any XC mountain bike racer needs a road bike for several reasons
1) They are fun.
Road bikes are made for one thing. To go fast on the road.
2) You can recover on a road bike
Unless you have easy gravel roads you just can't recover well off road. You get beat up, your legs have to work hard to get up anything, and mentally you can't take a breather cause you'll hit a tree
3)You can go harder on a road bike than you can on a mountain bike
-Intervals on the road are better than intervals on the mountain bike from a fitness perspective. You cannot go as hard on the mountain bike because you'll end up pinballin g into some trees. Of course it is still good to go race pace stuff on the mountain bike cause that is the only way to know what tech sections are going to feel like at speed. But from a training persepctive hard intervals are better on the road or trainer cause you don't have to worry about stacking it, or getting too beat up.
You can ride your mtn bike on the road of course, I did for years. 2 wheelsets one with knobbies one with slicks, etc. or hell just pump up your knobbies. BZZZZZZZ
But there is no feeling like flying on a road bike.
Nothing is cheap but there are some super sweet frames I've seen that would make a fine road bike for anyone.
Of course check ebay first. There are WAY more road bikes on auction than mountain bikes, it is amazing.
I'm partial to steel for road bikes, even though I just got Ti. For value steel of course beats Ti.
Here are some sweet one's I've seen
Kelly Bonestocks with sloping top tube on ebay
Salsa at Airbomb on sale though check with you LBS as Salsa is a brand of Quality Bike and the LBS can probably get a closeout deal too
Burley Wolf Creek
I really like the semi sloping top tubes.
* though this is an expensive example!!
The upslope seems to helps get the bars higher w/o the need for lots of spacers or a super high rise stem.
For someone who's main emphasis is mountain bike racing, I like to have my road bike position set up similar to my mountain bike in terms of the drop from the saddle to the top of the bars and the reach from the saddle to the bars. This drop is very little relative to what a lot of roadies and road racers have.
But my inflexible hamstrings dictate a higher position for my best power output. And the techincal riding dictates a higher bar for the mtn bike.