Peek mirror
That's the least expensive one I can remember finding online.
It needs specially marked cards; I don't generally see cards with the 'no peek' markings on them as readily available. Most of the customers for those cards (casinos) get them specially printed with their logo on the back, and request the special face.
You also need to train your crew to use it correctly.
My understanding is that the reason to use a no-peek device is to prevent bending the cards (which you can probably do by rotating them 90 degrees - long side toward the dealer - before peeking, and lift instead of bend) and to prevent the dealer from seeing the hole card (which can lead to an accidental tell to the players).
I understand you're already running an 8 deck shoe. Not sure where you're setting the cut card, but 1 deck from the back vs 2 decks from the back should get a few extra hands per shoe... I know you're not waiting for the dealers to shuffle, just waiting for the runners to send the next shoe over, which may or may not be a delay.
Short version: I don't think it will speed up the game.

1. Foremost among these (of course) is Beyond Counting, by James Grosjean. In my own experience, the most common blackjack hole-card read was paint/no-paint, that is, the ability to distinguish the cards Jack, Queen, King from the other cards. Grosjean refers to this as “PNP.”.
2. A natural blackjack beats any total of 21 that is composed of 3 or more cards. So, where does the house get its extra 0.11%? In the American game, where the dealer peeks before the players draw any cards, if the dealer checks his hole card card and turns up a blackjack, he immediately sweeps all bets off the table (other than a player’s.
3. Scientific Games has completed the acquisition of Tech Art, the gaming industry’s leading supplier of hole-card readers for blackjack. First announced in October, the acquisition of Tech Art will bring with it their innovative MAXTime 4H product, a combination of a blackjack hole-card reader and a chip tray, as well as the proprietary table games.

Blackjack Hole Card Reader Downloads

Blackjack Hole Card Reader

Blackjack Hole Card Reader Software

No annoying buttons to push or mirrors to squint at. No Peek 21 is the best security device the table can have! When the dealer has either an ace or a ten value card as his face card, he inserts the two cards into the No Peek 21 reader which senses the value of the bottom 'hole card' and triggers either a red or green light depending on whether the value of the two cards is twenty-one (21). Reader tell the dealer where to place the cards on the felt. The cards are move d to the correct range for the hole card. After the dealer has marked the card the action can begin. The layout used for “Down Under Blackjack” is very similar to a standard blackjack layout. The layout identifies the game as Down.