It all depends when you buy it we got a nice one last year kinda last minute for $15 but they can range from $15-$115 depends on when you go where you go and the tree itself the bigger and fuller the more expensive.
for my MIL (she's 46 too) she has everything she wants/needs so we are doing a "gifts in a jar" gift basket with some candles and stuff too I say GC for the 14 yr old or a BBW gift basket