Meaningful doesn't mean expensive. The $12 memorial tree is the one thing on this page that keeps growing after you send it. Everything else here is under $50 and chosen by the same standard as the rest of the store, which is that a grieving pet parent has to actually keep it.
What each price actually buys
Under $15 sit the two things on this page that do the most work. Pets Are Family is $11.99, and it's the book that tells a grieving pet parent their grief is proportionate, which is a sentence most of them haven't heard from anybody. A memorial tree is $12, planted in their pet's name, with a certificate that arrives by email carrying the name and the species of what's growing.
Collar picture frames land between $28 and $30, sized by collar length rather than by breed despite the names: the Garfield for cats and the Chihuahua for small dogs at $28, the Beagle at $29.99. In the same range you'll find the Pet Memorial Garden Kit at $29.99, growing pet-safe wildflowers from seed wafers, and pet-safe soy candles like Anywhere With You at $29.99. Burn times vary, so check the individual product page.
Above that and still under $50: the Tin Soy Candle Trio at $39, plus the crystal suncatchers, the Black Paw pin, the Forever In My Heart frame, and the Celtic knot keychain. Each of those pages carries its own price.
Questions, answered
I can't spend much. Does that show?
No. A certificate with their pet's name on it and a tree in the ground doesn't read as a budget decision, and neither does a candle. What reads as thoughtless is anything generic, at any price.
What's right for a coworker rather than a close friend?
Something that doesn't assume closeness. A tree, a candle, or the book. All three say the loss was real without claiming to know how they feel.
What arrives soonest?
The memorial tree. It's delivered by email, in minutes, which is what makes it the one to reach for when you heard the news an hour ago.
Can I combine a few?
Plenty of people do, usually one thing that arrives now and one that arrives later.