Trying to find a bow with replaceable limbs on that budget is going to be tough... My advice would be to find a used recurse in the poundage range you want, and see what happens. Let her shoot that for a year. If she falls in love, and wants a higher poundage bow, then move up. Tradgang.com and stickbow.com are food traditional archery sites with classifieds.
Also, call around to archery shops in your area and see if they carry any traditional bows. Many shops will let you try out trad bows if they have got them.
I just thought of Samick bows. I have no experience with them, but have heard good things.
Hope this helps. Just for FYI, I've owned 15-20 different recurve / longbows. I bought my wife a 32 lb. Root Ranger. She never wanted to go any higher in poundage.
Keep in mind most of these bows have a draw weight marking like 45 lbs at 28". If she I'd only drawing 24" it will be less weight. Around 3-4 lbs/inch roughly