I like that idea, it shouldn't be expensive, basically it appears that you tap into your existing in ground plumbing (or even easier
attach to your hose bib)and run small heads above ground by each plant maybe hiding 1/4" tubing under the mulch.
kit for 150 plants is $120 plus a $25 timer, total $150
Contains everything you will need to go from hose bibb (faucet) to your plants. Waters up to 150 plants. Take-Apart Flag Emitters attach directly to 1/2" solid tubing. The number of plants is an estimate based on each container receiving one drip emitter. Larger plants should get two drip emitters
see install book
.