I only have Bonnie Bonnets, and she has quite a special place in my collection since she was from a TP member long ago, back when I was barely starting out So my vote’s for her!
I love YumYum and Nightglider, their color schemes and symbols go really well together. They seem to be really popular and expensive because of this though

My most recent find was the unscented Retro Y2 Rainbow gift set for about $14 on eBay! Shipping bumped it up to $26, but that was still quite cheap considering how much the unscented set went for last year 
My favorite story though was the gallon bags full of ponies from the flea market, each was $5. From those bags, some of the ponies I’ve gotten were:
-Almost full set of Inspirational Words Core 7 ponies.
-Tex with hat
-Little Flitter
-Starflower
-Kingsley
-Princess Tiffany/Pearl
-Close to complete Y2 Unicorn set!
-FS Applejack with some of her accessories!

And last but not least, the 2003 Winter ponies MIB for $10!

She’s very cute! It’s just odd how her name is Mistletoe but her cutie mark is a bunch of ornaments 

Wow, she looks stunning!

Ponyland Press has some simple tutorials on curls, but they’re more G1 oriented. However, I’ve used these on other gens just fine :http://www.ponylandpress.com/care/salon/styling.shtml

Night Shine doesn’t seem very “Night-Shiny” to me...
However, Bumble Hum and Rise-a-Shine (Rise-n-shine?) are very cute!

Thanks for the heads up! $20 is a bit much, ack. I'm curious what the MSRP is.

Considering she’s a gimmicky pony, I’m afraid that’ll be her price range 
However, she’s described as a 6.5-inch pony, so she won’t be small.

EDIT: How much do y’all wanna bet she’ll show up commonly with haircuts in some time? 

Tough one... maybe Brazilian Wind Whistler, Mexican alt. Peppermint Crunch and Mexican Rainbow Medley.