I've not read the (already many) responses on this thread, so forgive me if this is redundant, but I think that it can make a lot of difference how many miles you can do in a day, how much elevation gain/loss you (realistically) anticipate doing. As part of a PCT thru-hike, I went through there starting in early June when there's lots of snow, but key was that I (and all PCT thru-hikers) had hiked 700 miles to get to the start of the Sierras, and could do pretty decent miles. The result was that it was not difficult to follow the old adage of "walk high and sleep low".

When "walking high" I was fine with a wind shirt over a hiking shirt, with the key there that you don't stop for long breaks that way. Definitely gloves or mittens however (and I strongly recommend mittens of the two).

When "sleeping low", I had a thermawrap jacket and a thermawrap vest that I could layer, but in fact I rarely needed the vest. Sleeping every night below the snow line, just cooked and ate, crawled into the sleeping bag and that was it.

But if your process is different and/or your mileage (such that you might end up sleeping at higher elevations) or your metabolism ... etc etc. Pretty hard to calibrate this stuff among different people.

Since you (O.P.) say you're taking the trail slowly and won't be jumping into the bags right away --- I can't really comment. I was on a snowshoe and winter camping trip with a group this weekend, and I had cold feet a lot, which I pretty much never do --- because of a lot of built-in "sitting around" time that I'm not used to. This stuff can vary so much.

Oh, one somewhat random comment I read on another thread recently --- Cabelas is selling their 650 fill down vest for $20 right now, this might be well within your budget (if a size medium or small will fit you).