In deciding whether an outfit is 'office appropriate' always remind yourself that the two piece suit is really workplace standard for men and women - judge your planned outfit by imagining yourself giving a presentation to a room full of people wearing suits and ask yourself would you feel out of place or too casual.
The truth is, on a smaller budget it is hard to do a good suit - high street brands just don't do the suit justice and in many ways it is because the suit is the gold standard of tailoring and high street brands are geared toward making a garment to a low price. I think every working woman should have 2 suits in her wardrobe eventually, but you should try and have one custom made and it may take quite a few years of working before you can afford one. I bought my first suit after 6 years of working - it's a black crepe pants suit and cost more than any item I own. I can wear both the pants and the jacket separately if I want and together it looks brilliant.
Until you're in the zone for the suit, I'd make a list of items that suit your working environment, then another list of items that suit your personal taste and then see how well the lists match. I am short and have a petite build, with an unfortunate large bust. I am absolutely with you on the 'no button up shirts' stand. I can do neat blouses with a little detail and love a good pencil skirt. I do wear a pair of stunning black trousers (silk/wool blend is the best if you can find it - the most brilliant combination) with non matching jackets. I love a dress and longer coat combination.
It is true as you say that 'work clothes' as marketed to us by high street brands are generally uninspiring and not at all flattering. The trick I think is to find ways to pair great separates. If you don't want to do a suit jacket, throw a trench on over pants and a top and carry a collared cardigan in your bag in case you have to cover up for a meeting. If you prefer a less structured look for your clothes, try bringing in some structure with your accessories - a classic nicely detailed pump and classic bag will formalise an outfit of separates.
We spend so much time at work that it's important to make sure that your clothes make you feel confident and professional. It sounds like a lot of effort, but the thing is, once you've thought a bit about how you want to dress for work, you don't ever have to spend any time in your working day thinking 'Do I look ok in this?' You can just get on with your job
I hate work clothes
My Favorites-- Gucci belt bag, Gucci Bucket Tote, Coach Carly and my Louis Vuitton Manhattan PM.
Just tryna remain debt free 
