Munster (on WargamerAU) advised that
NaW figures match well with Newline Design (small 20mm) but are much bigger than AB or CGM. 1/72nd infantry in plastics sort of match up, the cavalry for those is usually a bit spindly next to the metal ones
At 1500pts you tend to need 8-10 battalions of infantry (28 fig each), 2-3 cavalry regiments (12 fig) and 1-2 battery of artillery (3 guns + 1 limber) and 4-6 general figures.
If ordering I'd go for the sole UK supplier (Battlefield Models) rather than direct.
From the Man at War website
BRBX01: British Infantry Brigade £47.00So as a rough order of magnitude it looks like if using the Man at War figures you'd need a couple of the Brigade boxes, and a box each of cavalry and artillery and then add more models as required. So that's appprox £150 or about $300 to get started.
4 infantry battalions, 2 mounted officers, unit bases
114 foot figures, 2 mounted figures.
BRBX02: British Light Dragoons Brigade £32.25
2 cavalry regiments, 2 mounted officers, unit bases
26 mounted figures
BRBX03: British Foot Artillery £23.10
1 foot artillery battery, 1 foot artillery limber and unit bases.
14 artillerymen, 4 guns (with 9 pdr, 6 pdr or howitzer option), 1 complete limber (including horses and artillery drivers
BRBL12: British Line Infantry Battalion £12.65
1 British Line Infantry Battalion, unit bases
24 foot figures, 4 skirmish figures
Munster recommended
For Brits
1-2 Brigade of BitsUsing NAW boxes
1-2 Brigade of allies (cannon fodder)
2 btty
1 light or heavy brigade (3 light or 2-4 heavy regiments per brigade)
2-3 x inf boxeswould give you a fair force
1 x horse art
1 x foot art
1 x hvy cav
1 x scotts grey blister
Capitan make company
level rule set and miniatures for the Napoleonic era.
The figures are 15mm/18mm and the army packs contain approx 41 infantry, 12
cavalry and 1 gun for "on special" price of £ 21.00 or non-discount
price of £35. Man at War were selling their sets for about 42p per
infantry figure and £1.24 per cavalry figure and about £4 per gun team which
would suggest an equivalent price of about £36 per Capitan set. It seems that the figures ranges (both from Spanish companies) are pretty
much aligned in cost per figure.
According to
http://theminiaturespage.com/man/warmodelling/ there is a relationship
between Warmodelling Miniatures and Capitan Miniatures.
Infantry battalions - 6 bases of 4 figures
Cavalry regiments - 4 bases of 3 figures
Infantry - 4 figures in 2 ranks on 26mm (w) x 32mm
Skirmish - 2 figures in 1 rank on 30mm (w) x 15mm
Cavalry - 3 figures in 1 rank on 45mm x 40mm
Artillery - cavalry base

Other games systems for 15-20mm figures often have 4 40x30 bases for infantry, so 80mm x 60mm for an infantry unit which pretty much matches the NaW 78mm x 64 mm unit size.