No, you're not unreasonable to ask! Dressing for your shape, knowing your personal style, picking the right colours for your skin tone, and being mindful of fabric choices: that's all there is to it, really.
I don't think you have to spend loads of money most of my stuff comes from Ebay, new, tagged, and I don't like spending money, so most of my bargains cost about a tenner each including p+p! I think Primark is great, price-wise, and I've had a few good bits in there over the years, but I couldn't rely on it for my whole wardrobe. I can't wear their ordinary jeans: they're just not cut right for my body shape, the rise is always too low and the leg ratio is always a bit weird on me, (so I go to M&S!) but I have a skinny, shorter-legged friend who reckons they're great. I hate that they do loads of things in polyester chiffon I steer away from that kind of thing. Some people can get away with it, but I'm not one of those people.
I always find a gem or two in Primark, though, such as... the year before last it was a pair of coated high waist black jeggings for £15: I wore them everywhere, dressed them up, dressed them down, and got two winters' wear out of them. They went perfectly with my other winter 'rock chick' type pieces, and they looked way more expensive than £15.
Last year there was a white and navy striped linen tailored summer blazer, excellent quality, not lined, neat pockets and lapels, cut well, and I would've easily paid three times as much as I paid for it (was only £20) and I would've still felt like it was a bargain. I wore it with blue jeans, trainers and a basic t-shirt and I'll be wearing it again this summer, too, probably with a white t-shirt, white sandals, and some navy cropped linen trousers I got from monsoon for £40. (These outfits probably sound naff to everyone else, but they work for me).
My 'secret' is... accessories. I like big earrings, quirky necklaces, chunky bangles, that kind of thing -- (not all at once though!) I know it's not what's 'cool' right now, but it's my 'finishing touch', and it works for me. I'm kind of... art teacher vibe, a bit preppy, a bit rock n roll, a bit vintage. Maybe you need some 'signature' thing: cute hats, neon tights, metallic shoes, bright red nails, whatever, and then you can always 'upgrade' your Primarni bits with something that's 'just right' for you...? Happy hunting...