Agree with the fact that it's the childcare or the forfeited salary that is your major expense. Everything else pales into comparison.
Re "the stuff"
The things they recommend that you get new are cot mattresses and car seats, although must confess I got given my Stage 1 car seat second hand by a friend. I prob wouldn't buy one from a stranger. You can often get good deals in places like Halfords on "last years" model car seats which are just as good/safe.
Re clothes, don't buy "outfits" for babies under 3 mo (poss even 6 mo). What you need is many multipacks of sleep suits and onesies/vests that wash like rags. I like the Mothercare ones as they come with built in scratch mitts. You can sometimes find people selling whole bags of these basics as a job lot. If you're planning more than one child, get a lot of white/neutrals. With gender scans so common now, baby clothes do tend to be very pink or blue. Yeah, it doesnt matter really, but you get bored of saying "No actually it's a girl but she's got an older brother and I'm damned if i'm buying everything again"
Most people these days only have 1 or 2 kids so secondhand stuff is often really great quality. I got all my Grobags on ebay for around £5 each, whereas they retail new at £25. Got a travel cot for £20 (retails at £99) and you'd not have thought it'd ever been used (not that you need a travel cot right now- that's just an example)
You may be able to borrow things from friends who are between babies as well. I have lent loads of stuff like breast pumps, swaddles, play gyms, cot mobiles, jumperoo etc and also borrowed a fair bit of stuff that only gets used for a few months per baby.
Although I know it can sound "grabby" I'd also make a list of things you need so that if friends/relatives tell you that they want to buy something, they buy something you actually need. Give them a free hand and you risk receiving one beautiful, embroidered, handwash only muslin, when actually you wanted a 10 pack of plain ones 
Good luck TTC