I'm a swim mom from Wisconsin chiming in. First of all, no kneeskin technical suit will fit the 8-year old. End of story. I would hazard to say that very few 8-year olds are big enough for one.
My own 14-year old DD could not fit into a kneeskin until she was 12 (almost 13). She swam in a size 20 A3 Stealth and that was for Central Zones. She qualified in a size 22 Speedo LZR Pro tank (the black one with the gold trim). The Speedo LZR Pro kneeskin would not fit. I just bought her a Speedo LZR Elite 2 with the pink leg in a size 22 for Wisconsin State (and fingers crossed Central Zones) ... the price was ...

. She's 5"4 and 120 lbs of solid muscle and wears a 28 practice suit.
For those swim parents who say you don't need a tech suit for your 12-year old, I disagree. We changed teams this year so my DD could swim with her High School friends. There was a big difference in tech suit attitude between the two teams. If my DD wore a team suit at meets with the old team she would stick out like a sore thumb. Our old team had a very lax attitude about tech suits. Most of the girls 10 and up wore them all the time to just about every meet. Only the slower kids wore the team suits. Her new team does NOT allow the kids to wear tech suits without the permission of their coach. My DD will swim regionals next week (sounds like your "districts") to try to pick up a couple more USA State cuts and I am not sure if she will be allowed to wear her tech suit or if she'll have to wear the team suit. Your team sounds like our old team.
One thing to consider is if your team has a sponsor. Our current team is a Speedo team and the elite swimmers are required to swim in a Speedo suit (unless it does not fit). *sigh* That's why I had to shell out the big bucks for the LZR Elite 2. I tried to measure my DD and bought a LZR Elite on eBay a few weeks ago but she couldn't get it on

. I resold the suit and sucked it up and had her fitted at our local swim shop for 3 times more. I was very bummed because I had good luck with eBay before but apparently the LZR Elite was a crappy suit and impossible to get on. Her Elite 2 is a smaller size than that Elite I purchased and went on in a few minutes. If your team requires a certain brand, you are have fewer choices.
There are good "starter" tech suits like the TYR Fusion and the Speedo PowerPlus. They should run you less than $100 each. They do not have the same compression or as water repellant as the more expensive suits, but they are comfortable and it gives the kids a psychological boost. If you want to chance it, the Fusion is on sale at Metro Swimshop for $69 with free shipping (
http://www.metroswimshop.com/produc...gclid=CN-nzIOszLwCFStgMgodrDcAMA#.Uv5tY86cfRI). I bought two sizes from them for my DD last year (to help save her good suit for better meets) and returned the one that didn't fit. Returns were very simple. I would have her try on the suits in front of your coach or another swim mom. The suits should be very snug. It is not unusual to see older swimmer girls with sports bras on and the top of the kneeskins off their shoulders to their waist.