An old HP SA or VNA is just that, old. I found a refurbished and calibrated HP SA on eBay for the same price as the Siglent SSA3021X. If it were a 5-10 year old unit I'd buy it in a heartbeat, but at 15-20 years old there are too many potential problems. The last time I used my HP 8601A sweeper it was fine. Now it has a PS fault. I've fixed almost all my gear at one time or another. My first good scope was a 20+ year old Dumont 1060 with a 30 day warranty. After about 6 weeks the horizontal sweep died. My recurrent sweep 5 MHz Heathkit was not up to the task of fixing it. Eventually I got a wonky Tek 465 that worked well enough to track down and fix the bad solder joints in the Dumont, after which I fixed the bad solder joints in the 465. Unfortunately I spent so much time fixing gear I never made any progress on my QRP transceiver project.
When I started back playing with electronics I bought a Rigol DS1102E because I just couldn't face the Dumont and Tek. I never even turned them on to see how they were after sitting idle for 15 years.
Thirty five years ago I built a DC 40 M receiver which did not work. At the time I had no access to anything other than my Heathkit scope and a DMM. I strongly suspected that the hand wound toroid coils were the issue, but no way to test them. I was pursuing a PhD at the time. So I had no budget and I was not an EE, so no access to the school labs. When I got the 8601A it confirmed that the passband was off by 400 KHz.
I still want to build radios and other test gear, mostly the latter. So I need to build or buy filters. An SNA is sufficient. I'd love a VNA. I'm hoping to build one using the LimeSDR boards. My biggest interest is designing test gear that someone with limited budget can afford. The LimeSDR mini looks as if it might make a pretty good SA.
True wealth is being able to ignore the subject of money with impunity. The easiest way to achieve that is hard work and thrift.