okay, i have very long wavy/curly hair and can't afford to buy expensive products because conditioner only lasts a week for me. As far as a mid-priced product that goes a long way (ie. the conditioner doesn't water out) I swear by the Infusium line, try a different one each time till you find the right chemistry (their ingredients are super sciencey, less herbally, but pretty damn good as far as the chemistry of hair moisturizing goes, sometimes herbal doesn't mean better cause our hair is actually a complex of various minerals & amino acids that are well served by minerals & amino acids).

I am a strong proponent of mixing it up too, and the Citre Shine line, is probably the best bargain out there. I really only endorse their Daily Revitalizing Conditioner (I just wasn't happy with the others). So I do Infusium for 3 weeks, Citre Shine one week.

If you got curls and you're putting gunk invest in a quality shampoo that clarifies but doesn't strip the oils. Shampoo lasts alot longer than conditioner so splurge if you have a mind to. Right now I'm waiting for a bottle of yucky stuff to run out, and when it does I'll probably get back into the Giovanni line, i really like their stuff for cleansing and nourishing.

As for nice curls, they actually start long before the product. Here's what works for me:
-trim little bit every 3-4 months (i cannot understate how important this is to maintain bounce). you may want to throw some subtle shape/layers into it to if you're going for fullness. do not ever cut your hair straight across if you have curls/waves, you're setting yourself up for frizz. give it a nice rounded bottom so that if you have it all combed onto your shoulders/back the sides slope up an inch or two from the center, a nice curve workes better with curls than a sharp V, although that can be very dramatic too. if your hair is getting long enough for you to cut it yourself i have a great method but i'll skip that now. if your hair is above shoulder length then the reverse curve is good, longer in front, shorter in back, it really brings out the neck, face and draws attention to pretty nape curls

-when conditioning your hair, finger comb the tangles out. this gets yucky hair all over your hands but better than down the drain, and better than using a comb or brush when your hair's wet because that's when it is most fragile. so finger comb out the snarls while conditioner is soaking. give yourself a nice scalp massage at this point too. once you get the nack of finger combing this should take no longer than 2 minutes. and load up on the conditioner if you have serious snarls. (out of respect to roommates try to remember to throw the hairball away, it's scary) i personally always leave a little sheen of conditioner in my hair, i never wash it entirely out to squeaky clean.

-apply leave in conditioner (again i love Infusium; Redken has a more expensive one, Anti-Snap that some people adore but I felt was good, maybe a little overrated). The best is if you can get it in a spray bottle. Focus on the underside (by the nape of your neck), the ends all over, the longer strands of delicate baby hairs at the front; and the part where it inevitably gets damaged from ponytail wearing (ie. the middle section right at the back of your head).

-comb using a wide toothed comb. i like wooden. or finger comb. or don't comb at all. experiment with all of these to find out which results in the shiniest, most defined curls for you. when i want waves i comb, when i want thick spirals i finger comb, when i want shiny flatter spirals i don't comb at all. sometimes the hair can be unreliable so...a loose braid while its still wet, let braid dry, as it dries it will become thicker and tighten up. let it loose and your own curl shape will emerge, while the top is sleeker, if you hair is curly then the pony tail line can be resolved by some fluffs and a little water mist. it's quite lovely.

-as far as curl enhancing products, i haven't looked hard for one yet cause humidity and wind here in Hawai'i make most products into goopy mud down the back of my neck. oils tend to be the most common thing here, coconut oil especially. but i can't endorse that for you without seeing your hair. for some people it's a great way to condition and define curls, for others it just weighs them down. the key is NOT using too much of any product. if your curls can stand up on their own, i really really like paul mitchell's Foaming Pomade as a do-all gel/slickster/de-frizzer/curl definer, curly-Q maker. it never gets sticky, never weighs my hair down, and a wee lil bit goes a long way.

speaking of long....

hey one more thing (sorry, you caught my passion!), besides chemical perms i really doubt that any products will make wavy hair curly. curli-ness depends primarily on the shape of the hair follicle, which then forms the shape of the hair as it grows out (kind of like using scissors to make package bows curly). straight hair is a wide open circular follicle, while curly hair is more of an oval slit. these follicle shapes are detemined by a fun combo of genetics and hormones. it may be that your mom and sis have a slightly different inheritance than you, or maybe cause they're older and body things have changed to a curlier side? but regular hair products will not make super curls out of waves, they might give some momentary oomph and definition however.