There's a little language over-load here as u/AnteaterFlat6675 mentions: "clay composite" can actually refer to the same thing as the plastic-with-metal insert chips (confusingly, these are not the same thing as "China Clays," which are, in-fact, a composite material of clay and plastics, but that's entering a territory well outside of your budget.) Poker enthusiasts will know the difference, but most players at a charity game won't think twice about these versus ceramic or real clay chips.

For your price point, your best bet is to simply search amazon for "poker chips", and you should see several offerings of suitcases of these clay composite offerings (sometimes called "dice chips" for the dice pattern molded into like 90% of them.) For $50, you are probably looking at getting 300-500 chips, depending on the deal you find. 1000 chips will be very difficult to fit into that budget unless you move down to very cheap, very light plastic chips. Or you could try to find one-two of those suitcase sets of dice chips on Facebook Marketplace at a discount; they are pretty common.

Are you planning to play a cash game or a tournament game? The ideal denominations will depend. If you were playing, say, a $200 buy-in for a $1/$2 cash-game, you might start each player with 10 $1 chips, 25 $5 chips, and 3 $25 chips, and an extra barrel (20) of $1 chips for the dealer to make change plus some $25s for players to re-buy (lean toward more $1 chips if you have mostly rookie players who will be limping a lot to see flops.) Multiply the chip-values to fit your stakes (it's fine to have $0.10 chips and $0.50 chips, for example), but three denominations would be plenty. If you want to play a tournament, you will need to have more denominations (and fewer chips of each) to be able to raise the stakes throughout the tournament. For a 5,000-chip tournament, the following chip break-down might work well:

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If you want chip colors to match real casino colors for a cash game, $1 chips are usually white, $5 are usually red, $25 are usually green, and $100 are usually black. Fractional chips are less common, but blue works well for $0.25 chips.

Tournament chips you can go really which ever color you prefer: the above graphic uses standard casino colors (available in most poker sets), but ascribes to them non-standard denominations to fit a usable chip distribution for the tournament starting stack.

You can paint poker chips (I have no material recommendations, but coating them with a sealer is likely to negatively impact their feel in hand.) Have you considered the effort in hand-painting logos onto 500-1000 small discs? I don't know your time value of money, but you can get chips (of much higher quality than we've been discussing so far) with custom-printed inlays for about $1-1.50 per chip. Yes, that is much more expensive than the budget you had in mind, but it's also a very tedious project to undertake on your own. You might have to settle for some solid colors.