These cards are both under ten dollars and have relatively high hit rates, so although they won't help you strike it rich, they will help you expand your Pikachu collection
As for continuous effects, red has a number of great options now
6 Spirit Of The Labyrinth/ Eidolon Of Rhetoric Stop Opponents From Playing The Game Enchantment Creatures Costs: 1 Generic and 1 White Mana, 2 Generic and 1 White Mana This entry consists of two cards with similar effects that can be used individually or in tandem to practically lock an opponent out of playing the game
Set Code: s9 Click on any card to see more graded card prices, historic prices, and past sales
(2/29/2020) By default, you are limited to cards legal in the format you're playing
SANCTIFIER EN-VEC I think Protection is really underrated in Commander, and especially so on creatures that can jam in or block in the early to mid game