We recently bought a sports horse for dd - there was nothing that fit your description for less than £10,000 and most were a good deal more.
5 stage vetting including X-rays ranged from £700-£1000 (we’re in the south east so may be cheaper depending on where you are).
Transport was £280
Month’s deposit plus first month livery in advance £1200
Tack - if you’re starting from scratch, £800+ for saddle, £100-200 for bridle, £50-100 for girth, £50? for bit(s) (DD’s horse has gone through quite a few combinations and annoyingly goes best in a little-known (and therefore expensive) Dutch brand). £100+ for saddler to check saddle fit and reflock/adjust. £40+ for stirrups, £30+ for stirrup leathers (don’t get cheaper ones - dd had one snap as she was going over a jump which could have been really nasty)
Saddle pads/numnahs - £30 upwards depending on how matchy-matchy you want to be
DD’s horse only has XC boots which were about £100 for the set but some also have boots for jumping, turnout etc
Travel boots and tail guard - £50+
Head collars - £15+ and £40+ for a leather one for travelling
Rugs - vary enormously in price - anything from £20 for a fleece to several hundred pounds for a top of the range Rambo turnout with liner system. Rugs are very horse-dependent - some brands fit different horses much better than others (typically ours fits Rambo best but they are brilliant if eye wateringly expensive). Wait until you get the horse before buying any so you know what size you need.
Yard and feed stuff depends on how you’re planning to keep the horse - if it’s going to be on full livery, then you probably won’t need anything else. If it’s going to be on DIY or at home then budget for another £200-ish for mucking out tools, haynet, buckets etc
Good luck!